You're probably not forgetting anything, but without desserts, they may wonder why you want to go OOP. What is the price point for the snacks you are including for OOP? Are you allowing any desserts at TS to share? Did you include drinks in your OOP? Don't get me wrong. My family does way better OOP than DDP, but that is because we PREFER to drink water with our meals and we PREFER to order one dessert with TS to share instead of all four of us getting two desserts per day. You need to take into account how your party WANTS to eat while on vacation. If everyone wants their own dessert and wants to get high dollar snacks, then you might be better off with DDP.