I just wanted to point out - we went when my son was 9 months old, and I didn't feel like this at all! We walked off the ship a little while after they had docked, got on a tram to the beach, got a wagon for my son/our stuff, found many chairs all together, and then had the water slides to ourselves for probably a good hour.
Caveats:
-We were on the Wonder, which is a smaller ship
-We were sailing early May, not exactly high season, and it was very windy & slightly chilly
-We are morning people - by afternoon the beach had filled up (& the wind had gone down somewhat). I suppose at that point a cabana might have been nice to have a quiet place to nap the baby, but he was so wired we ended up having to take him onto the ship to calm down and relax in the dark/quiet cabin.
Everyone's priorities are different, of course, but I wanted to give you some info from that side of the equation