I hear yah! I try to eat healthy when I travel too. I allow myself one treat per day at WDW, because I know I'll do a ton of walking to make up for it. If I don't limit myself to one treat, than it turns into 50 treats!
Anyways, heres what I've found so far in my travels:
Tangierine Cafe in Morocco/Epcot: the hummus and taboule are delicious and the chicken is roasted and not greasy at all.
Sunshine Seasons in the Land/Epcot: lots of great salad choices, fresh vegetable options galore, lean deli meat, grilled chicken, salmon, and tuna options
Pretty much every CS place offers grilled chicken sandwiches and chicken salads. Many places also offer veggie burgers which I think are Gardenburger brand. TS places will accomodate your every dietary need! I think as long as you choose lean & grilled meats, ask for no sauce or sauce on the side, and ask for your veggies steamed, you should be fine!
They also sell lots of fresh fruit and fruit salads, fat free frozen yogurts, regular yogurt no sugar added ice cream, lowfat pudding, sugarfree jello, etc...You can substitute fries for fruit and raw veggies at most places.
As long as you have willpower to say no to the other stuff, you should be fine with options everywhere you go!