Phuong, no guarantees about rough weather, but generally late Nov. is past the worst-weather season. I haven't sailed so. Carib., but have done western, and found the seas a bit rough, though not too bad, and certainly not scary. Depending on your children's ages, you may be able to get medication to control the seasick tendencies - there is one (Bonine) that works well for me, but check with your pediatrician first to make sure it's ok for the kids. I think the kids will have such a great time they won't even think about it! These big ships are well stabilized, and unless it's very rough, you probably will only barely feel any motion at all.
As far as cabins go, my personal feeling is that an outside cabin (with window) is best, especially for those who can get motion sickness. (I always had to be by the window and looking out at the horizon & distant scenery in a car too - and still do!) If possible, choose a lower deck, and a cabin amidships (about halfway between the front & back ends of the ship). This minimizes motion as well. Be aware that on some ships you might encounter some vibration from engines & other mechanicals in the lowest-deck cabins, but aiming for the 2nd deck from the bottom up to the middle decks is still good for motion.