For us it's worth it. We like to eat at the nice T/S locations.
Another consideration -
DH is fine budgeting to pay for the total package (whatever it ends up being - with or without DDP etc) but if we don't pre-pay for the DDP, he will penny pinch and nit pick over every single meal while we're there. It's MISERABLE when he's being like that. We end up eating more counter service (which neither of us like that much) because he has to see the dining bill at each and every meal and it stresses him out. (And, no, saving the money ahead of time for the meals we'd eat there OOP doesn't matter - it's a gripe/stress with every single meal paid for OOP. With the package it's one gripe when the final bill is due and then it's over - and he fusses the same way whether it has the DDP or not. Just get it over with once and be done with it!) With the DDP, when the bill comes, he now looks at it and says "Wow! Look how much we saved!" simply because the money isn't coming out of his pocket at that moment.
Remember, the 22 month old won't cost anything on the DDP - they eat free off your plate(s) which, at buffets, mean they can eat anything there free.