I think age 1 is GREAT - the child is basically free, and the hourly nursery rate is a steal - much cheaper than paying full fare when they turn 3! Just make sure to book your nursery hours ASAP when you check-in and book online activities! If you tell us which ship are you on we can give you more specific tips.
Some tips:
- bring water shoes - great for the splash pad on board (it is slippery) and also great for
Castaway Cay - sometimes there can be some rocks/coral-y stuff on the bottom (but not much)
- Have the 4-yo wear her swimsuit under clothes when you board the ship - that way she can go straight to slides/pool when boarding
- get an earlier port arrival time so you can a) eat lunch on ship and b) maximize fun time on ship
- If you're on Dream/Fantasy they have built-in nightlights in the ceiling so no need to bring one - I don't think Magic/Wonder has that feature but maybe someone else can chime in
- recommend bringing bottled water and a few snacks to have in stateroom, just in case small kids don't feel like waiting on room service or leaving room to eat - also you and your spouse can bring 2 bottles of wine each on board or a six-pack of beer each
- recommend bringing a white noise machine, it really helps improve your sleeping experience, drowns out kids running by in hallway, etc. Or download white noise app on phone.
- get floats from dollar store for Castaway Cay, packs flat, can throw away w/out guilt at end of trip