I have only been to Serenity Bay as it is 18+ and I don't have kids - so be aware that your kids will not be allowed to go with you if you choose to go - so I cannot compare the food, but I've always been happy with the food there (I've had burgers, hot dogs, and steak at various times...they usually have ribs, but I don't like those so I never have them, and on occasion if CC day falls after the night they have lobster, they have lobster at SB if there is any left over).
But atmosphere-wise I definitely find it calmer than anywhere on the ship. Quieter. I don't have to worry that a kid who may or may not be in my line of vision is going to dart out in front of me while I'm carrying my plate (yes, that happened in Cabanas once and the plate went everywhere as I struggled to not fall on the child - of course no parent was in sight). So the calm and peacefulness is exactly what I want for a day at the beach.