Welcome to Cruisemates, and to the world of cruising,and, congrats to you both!
Right off the bat, reading your post, I thought Celebrity, the Solstice class ships, but, with the dates you need, they may be in Europe by then. Please consult with a cruise travel specialist, and let them walk you through the process, especially as first time cruisers.
Ths Solstice class has stunning pool decks, some have beautiful lawns on the upper deck..delicious dining,and all in upscale setting...I loved my time on the Eclipse...
There is plenty to do and see on the RCI ships with out the flowrider and rock wall, so take that into consideration...Make the call and see exacltly what your options are,mand once you select your ship, please come back and lt us help you in any way we can, ok?