A lot has changed, huh? It's really crazy how much things have changed sometimes when I really sit and think about it.
During the time you're going, MK sit downs are in high demand. Look into Skippers Canteen or consider eating at a QS spot at an unconventional time like 11a or 2-3p as it would (hopefully) be less crowded and you could sit and relax a bit more. As far as other spots go in other parks, I would just go online to play around with what's available as you never know with Disney. Sometimes typically high trafficked places would surprise you with availability according to day, time, and events that day or week.
I'm not sure what your plans allow, but I'd even consider a TS lunch at a resort. They'd likely have more availability and would add a nice level of relaxation to the middle of your day.
Good luck!