For me - definitely the one bedroom - more privacy and the hot tub. But it depends how much you like cooking! At least the dining plan is a good deal and will save you some cash. I don't know if you're allowed to do this, but maybe you could split your one bedroom stay into two different ressies and get the dining plan for part of it - then you could do a mixture of eating in and out.
Please - don't flame me anyone. As I have said - i don't know if it is allowable to do it this way - just an idea.
Me, I can't do without either - the dining plan offer was too good for us to pass up, and i now really find it difficult to stay in anything but a two bedroom. First it was a one bedroom - made that mistake at the start and there was no going back to a studio. Then we stayed in a two bedroom last trip and can't go back to a one bed. It was quite funny - when we got there the kids were complaining that i'd said they would get a seperate bedroom instead of the pull out. The unit was so huge that they couldn't find the bedroom!
Anyway - be prepared - if you stay in a one bedroom, it will really spoil you for the studios if you plan to stay in them in the future.