Wolfgang Puck Express (not Cafe-that's TS) is an excellent choice. As is Earl of Sandwich, as previously mentioned. If you don't want to go into one of the parks, that would be my choice. I personally think WPE is the best CS. We like the one by DQ a little better than the one in the Marketplace area (probably because when we were there last year they were out of all desserts except for the frozen yogurt-which I didn't care for

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Food courts at GF (Gasparilla Grill and Games) is another good choice. And it doesn't seem to get too busy either. They cook your lunch or dinner to order (as does, I believe Capt. Cooks at Poly). Artist Point at SS is another great choice, and again, doesn't seem to get too crowded. SS is a beautiful resort to check out.
In the parks-Cosmic Rays at MK (though it can be very busy and noisy); Flametree BBQ at AK-and you can sit in the shade by the water; Sunshine Season at Epcot has great choices, though again can get very busy and noisy. We also enjoy Tangierine Cafe. A little more exotic than SS.
If it was me and my DH (if I had one) and I wanted to get away for a nice adult break I would pick someplace at DTD. In the afternoon DTD isn't very busy so you can leisurely stroll around, take a ride on one of the boats (there are several docks at DTD). You can ride from one part of DTD to the other or even enjoy a nice ride up to Port Orleans. And hey, while there you could grab some beignets for dessert at POFQ.

A great way to start your Disney vacation.
Conversely, you can eat at one of the MK resort food courts and ride the monorail around. Getting off where you want, checking out all the resorts and maybe having an adult beverage (if you are into that) and even take a boat ride on the boats that travel from the resorts to MK.