Thanks for all the response y'all.
We're deciding mainly between a 7 day cruise on Oasis that leaves Miami and goes to Labadee, St. Thomas, San Juan, and CocoCay vs a 9 day cruise on Grandeur of the Seas which goes from Miami to the Dominican Republic, San Juan, CocoCay, St. Thomas, St. Croix and St. Maarten. Its my understanding St. Croix is less touristy (and everyone I know who've visited there was there for work at the oil refinery) and not sure how special Puerto Plata is, if the two extra days on the ship can be better spent visiting the Miami Beach and Everglades National Park.
Grandeur would be the second smallest ship we've been on (smaller than its sister the Enchantment of the Seas) and it has fewer restaurant selections and doesn't have the large water slides and zip lining on board. But the itinerary does seem a big more appealing since it includes TWO of the Virgin Islands (we had initially wanted to fly there and get a resort but that would be much more expensive) and St Maarten seems interesting (though Labadee as a private destinations sounds good too.) So the Grandeur cruise would be on a smaller ship but more days and more ports. If we go on Oasis, since there are large water slides on board I'll probably not pay extra on CocoCay for the amusement park section. Both CocoCay and Labadee look very appealing.
So far I've been on the Carnival Ectasy back in 2000 from Miami to the Bahamas, that ship is small compared to all the rest but that was my first cruise but I was impressed. Also been on the Enchantment of the Seas from Baltimore to Bermuda, then the Explorer of the Seas from Seattle to Alaska and Norwegian Getaway from New Orleans to Cozumel, Jamaica and Grand Cayman.
RCI ships seem better than Norwegian in that there are more places to relax and enjoy the ocean, Norwegian has more food selections but the restaurants take up a lot of space on the ships, also with Norwegian you have to pay to use the sauna and hot tub in the gym area while at least with Explorer of the Seas I didn't have to and they had a nice indoor hot tub.