Welcome aboard, Vicki!
I know that your kids will enjoy either of those two Port Adventures, as mine have loved both of them in Nassau, and our kids are the same age as yours! The
Discover Atlantis adventure is pretty amazing. That resort is certainly something to experience, and I know you'll love the replica of the lost city in the aquarium area. Pretty unreal! And there are shuttles bringing guests back every half hour or so from Atlantis, so you can come back whenever you'd like! We've also enjoyed the
Seaworld Explorer Semi-Sub with its gorgeous views under the sea!
I cannot tell you the times for those, as they vary based on sailing, but you will be able to choose those times when you begin online check-in 75 days prior to sailing, since you're a first time guest. However, I can tell you that they both usually offer a morning and later morning departure from the ship, so you can plan on choosing either time, and get the specifics of times once you begin online check-in. My family and I always choose the earliest option for our Port Adventures when they offer more than one time, and we do so for the reason you mentioned: to get back to the ship to relax when it's less crowded!
The ships are so large they never really feel overcrowded, but it is nice to return early from a day in Port while everyone else is still out exploring, and feel like you have the pool deck all to yourselves! There will be other guests there, of course, but the lines for the AquaDuck will be so much shorter, which is a big thing for my children! They love to ride over and over and over, so the shorter the line, the more trips down the tube they get!
I hope that helps as you continue planning, Vicki!
Marcy