Make sure you have whatever IDs RCL requires (look at their website) for your cruise for each individual (including children) for your particular cruise (eg, Passport, Driver license, birth certificate)
Step 0: Decide if you want to buy Travel Insurance, there is a limited amount of time to buy the insurance after making a first deposit if you want the pre-existing condition waiver.
Step 1: Get a current book out of the library by Moon and/or Lonely Planet that covers the cities you will be docking at. You might also want to look at " https://www.travelalaska.com/"
Step 1A: If you are doing My Time Dining (probably makes sense in Alaska since it is port heavy with varying return times) book those times NOW if possible. The buffets are OK however I personally like the sit down dinners, but I don't travel with children. The sit down dinners take some time and are multicourse events. I would try it at least once early in the cruise. At the sit down dinners you CAN (unless something drastic has occurred) order an extra entrée for your family to share and multiple appetizers and/or deserts. Just try to order what you will eat and not waste.
Step 1B: Depending on the ship there may be free and/or reasonably priced entertainment options that you can book for at sea days available in cruise planner. If there is something interesting book it NOW, you can always cancel within the time period provided in cruise planner. If there is a price, check every few days to see if the price drops.
Step 2: Ship based excursions can be but are not always more expensive. Decide if the ship based excursion is what you want vs doing it on your own. FYI, you don't have to do an excursion if you don't want to. You can just walk off the ship and explore on your own, Alaska is part of the US. The benefit of the ship based excursion is that things are planned out for you and they usually guarantee that you won't miss the ship or if you do they will get you to the next port. YOU DO NOT WANT TO BE THE PEOPLE RUNNING TO MEET THE SHIP, THE CRUISE SHIP WILL NOT WAIT FOR YOU IF YOU ARE LATE AND DID NOT BOOK THROUGH THEM. The downside of a ship based excursion is that there a lot of people on them and they are not flexible. If you find a ship provided excursion book it now and check the price every few days to see if it drops. You can usually cancel up to a few days before the sail date without a problem. Check the fine print. FYI, usually but not always there is a line to leave the ship and those on excursions will sometimes get off the ship before those who have not booked a cruise line excursion.
If a third party provides an excursion read the fine print. The ships generally try to meet the posted itinerary HOWEVER, the cruise line does NOT guarantee the itinerary and a cruise ship will sometimes miss a port or adjust the time it enters or leaves a port.
Step 3: Decide if you will be bringing any beverages on-board the ship. The last time I looked you are allowed to bring 2 bottles of wine (750ml) and a dozen 17 ounce softdrink/water bottles onboard at embarkation in your carry-on luggage. Look at RCL's website to see if this is still true. If it is decide if you want to bother. As was said above if you dink a lot you might want to think about a beverage package that includes alcohol (there are rules about both adults buying an alcohol package). There are also soda only packages that can be bought for the soda-holic There is also a refreshment package that can make sense. Also last time I looked a coffee card. Lots of Cruisecritic info on these. As was said above you don't have to buy any of these and just drink the free stuff and buy an occasional soda or cocktail. Personally when the refreshment package is $20 or less per day (not including tip) it makes sense for me and my wife however that is a personal choice, not everyone in the group needs to buy it. Prices do go up and down.
Step 4: You don't have to purchase any extra costing specialty meals. I have found the free food on RCCL adequate, do not expect 4 or 5 star dinning regardless of what the brochures say however I have always found something to eat that I was happy with. That said, if there is a specialty dining option you want see if the price is right and book it in the planner.
Step 5: Seattle is an interesting city and worth a day or 2 of sightseeing if you can swing it. Try not to fly in on the day of the cruise if you are flying. Best to be there a day or 2 before even if not sightseeing Seattle.
Step 6: WIFI is not free on the ship. Not sure purchasing it makes sense on an Alaska cruise however that is a personal decision.
Step 7: In your leisure look at the various articles about dos and don'ts and what to pack, etc.