Hello! So it looks like the other cruiser answered stuff about booking, tours, arrivals etc.
I'll try to provide what I can about Miami. Keep in mind, if you aren't from the Southern US, the heat/humidity in Miami at this time can be near unbearable. So, definitely pace yourselves : )
Can I ask about your interests? What types of things do you and your husband generally enjoy doing when visiting a city for travel/in general? I'll give some feedback on a few neighborhoods that are sort of "Central to Miami", but keep in mind, while it has a decent southbound rail line and one that connects to the airport, plus a few scattered pretty walkable neighborhoods, it is generally a driving person's city, and while there certainly are interesting attractions, it's not necessarily the most immediately visitor friendly city out there.
Miami Beach (Flamingo Lummus)
Flamingo Lummus is the name for the generally most walkable stretch of South Beach and the one many think of when thinking of the area. It is considered a world capital for Art Deco architecture (in fact, there are self guided, and guided walking tours that you will find easily with a Google Search), and it also does have a few decently important cultural venues (most notably, the Frank Gehry designed New World Symphony building which often has outdoor movie screenings in the evenings.). That said, for being considered the most walkable neighborhood in the south (WalkScore.com), behind the French Quarter, it is not necessarily so much a sightseeing district. The primary charms are shopping along Lincoln Road (pedestrianized center), and probably some boutique shopping on smaller side streets, surrounding that, the beach (obviously), nightlife (varying kinds, but with an emphasis on high end nightclubs, and I'm not sure you are partying types?), and food (all kinds really, but with an emphasis on iconic/nationally renowned places for varying Latin cuisines and Seafood. You can find surprisingly reasonably priced and authentic places for both among the chaos if you research well enough.
Downtown: The business, transit, etc. hub for the area. Very much a mixed bag. There is a shopping area called Bayside along the water which is extremely touristy, with a park next to it that runs along the intracoastal. In addition, just to the north is the Miami Heat arena, and past that you will find the city's art, science museums and performing arts center. Also, the Freedom Tower, which now acts as a museum/art gallery, and is historically considered the Ellis Island of the South/Latin America. However, while these places are all on/near the water, you won't want to go too far west from here, as if you do you'll wind up in Overtown, which is considered one of the city's more dangerous neighborhoods. The CBD itself (where the tall buildings are across from Bayside away from the water), doesn't have a ton of obvious attractions, and to be honest has a somewhat gritty feel (though you should feel completely okay during the day), and it does have a number of cool historic buildings to check out and local restaurants/coffee shops mixed in. Follow this route if you want to explore Downtown outside of Bayside: http://www.miami-beach-travelguide.c...town_walk.html
.. I'll include Brickell in with this as well, because it is connected to downtown by a free elevated monorail service, and is just across the river (which is also scenic to walk on). Brickell is known for having many of the city's highly acclaimed high end restaurants, and shopping complexes. Even if just window shopping, Brickell City Centre may be worth checking out over other local malls as it features postmodern design, and won't be as hot as the other two. I believe there are even hotels directly connected to the mall, which is also a transit center, so it give you an easy and safe option for staying/exploring while in town. You could probably even catch the Two Day Hop on Hop off bus route from right here.
Little Havana: Southwest 8th Street doesn't feel unsafe to me, but it also doesn't have a clean/whitewashed feel either, so it will give you somewhat of an idea of local life. I suppose one could call Versailles touristy, but the prices are great as is the quality, and it's truly an iconic eating experience. That said, the center of Little Havana neighborhood would probably be along Southwest 8th, between SW 13th and 19th (maybe don't walk that whole stretch though. It's not unsafe to, it's just that you'll be crossing streets and seeing certain nondescript stretches with Burger King, Domino's, etc. ). There are two stretches I would focus efforts on. One is between 18th/19th, where you can check out the Bay of Pigs Museum/Library, El Rey de Las Fritas (an iconic Cuban diner most famous for the torta burger), and maybe the neighboring supermarket or bakery. The second section of interest (perhaps more), would be the block between 14th/16th, with the Calle Ocho Walk of Fame (where you can get a picture with the "star" of Gloria Estefan or Julio Iglesias), watch the domino players in Maximo Gomez Park (about as Miami as you can get outside of catching Jai Alai somewhere), Azucar Ice Cream and Tower Theatre (I'm sure there are good restaurant spots too, but I'll let someone else pick those). There aren't a ton of places to stay around here, so, if you're looking to check this out, it will probably be as a day trip from downtown (or if you're looking to save money/stay in a quieter place, the airport area.)
Wynwood: This area doesn't have a ton of hotels either, it's main draw is being kind of a new/hip alternative to South Beach, but not on the beach of course. While there is certainly a trending young social scene, it is not as wild and crazy over here as Miami Beach would be. It is also the largest contiguous collection of grafitti murals of any city in the world, I believe, though I don't know if that claim is fact checked on their part. While I haven't been, I've heard nothing but positive things, and there are plenty of nice cafes/restaurants, shops and art galleries in the main section.
Airport/West Side (Sort of middle/upper middle class area west of airport, where there are a number of hotels at a decent value. Not a ton happening here, though Dolphin Mall may be a nice visit for rain or excessive midday heat, but it's quiet, more value for hotel than you may get in other areas, and not terribly far from any attractions unless you decide to be on the road at rush hour.
Miracle Mile/Gables: A few miles south and west of the main section of Havana, it's kind of a garden style suburb, nice enough main street with some shops, dining etc. It does not have as much unique personality/flair as some of the other places I mention, but it does feel nice and safe overall. If you are visiting Coral Gables area, perhaps visiting the University of Miami Campus or the Biltmore Hotel (esp. a beautiful piece of architecture), would be worthwhile. Or the Venetian Pool, for a few bucks you can swim in I believe maybe still the largest public pool in the US. I believe it is even spring fed. Another nice thing about these west side neighborhoods is that the Everglades, or Key Largo for snorkel/scuba, or the fruit farms of Homestead, are reasonable day trips.
Coconut Grove: The neighborhood in Miami that I plan to stay in next time I visit (in an AirBNB, as hotels are limited). It has a nice pedestrian area, with perhaps more of a uniform, historic streetscape than anywhere else I've found in Miami. It has a clean feel, but without feeling whitewashed, and also a kind of Bohemian/Latin flair. It is quite close to other urban neighborhoods including downtown, but is also easy going further out to suburbs. The prettiest beach I've been to in FL is at Cape Florida State Park at the end of Biscayne Key, and this neighborhood is right near the bridge for that (about a 25 minute drive). It is pretty cool that you can get to a place like that which feels almost like a private beach in the Caribbean if you time your arrival right. Really a top experience in the area. You're also very close to the Vizcaya Mansion and Gardens, which IMO at least so far is the best individual attraction I've seen in Miami. Really gorgeous and distinctive.
Don't rule out outlying areas if none of the places I mentioned match your tastes. The Palm Beaches provide a totally different atmosphere despite being an hour away. Kind of private/high fallutin I guess you could say, but overall the general atmosphere there is just quite nice. Fort Lauderdale is a bit of a combination between Miami and West Palm. Perhaps a bit bland, but more urban than WPB, and with a more clean feel to it than you'd find in Miami. If you decide to spend time here (it's only a 30-40 minute distance), then maybe take a canal tour. Hollywood Beach is pretty neat too, has a bit more of a California beach town style than most in FL with cafes/breweries and stuff directly on a boardwalk facing the beach. Probably my favorite beachfront area in FL.
If transit to the port is a priority, I would recommend staying in Brickell. This should do: https://www.google.com/maps/place/Al...!4d-80.1969418
I'm sure you'll find plenty happening within walking distance in this spot. Within a couple miles of port but yet will have a clean/safe feel to it.
Let me know if you have any additional questions! I actually live about a 40 minutes south of Tampa Bay, but Miami is only about 3 hours, and since it is kind of the closest "major" city to where I live now, and I have some affinity now for the Latin Food/Culture present there, I do feel a sense of ownership over it. I can honestly say I wasn't at all a fan the first couple times I visited. Found it characterless/horribly planned. However, on more recent visits I have come to appreciate more of it's urban charm (re: maybe mostly food, but who's counting), and I think it's taking some steps in the right direction on city planning, plus there's some cool architecture/sights beneath the facade. Need to plan another visit at some point (maybe even just a long day trip), as I can say that I haven't even done a number of the things I recommended to you (Wynwood, etc.) Bon voyage!