One of our favorite places to eat was at Whole Foods in Columbus Circle. It's at the SW corner of Central Park, kinda. Maybe a 10 min walk to Times Square? They have multiple different buffet type areas- hot food, picnic food, sandwiches, an amazing salad bar, a cold salads bar (potato, seaweed, etc), an indian food station, chinese station, etc. There's a large food court so you can eat inside, or take it across the street to the park!
We also liked Brooklyn Deli on W57th? 56th? near 7th Ave., but you'd want reservations and the prices are on a par with a lot of NYC; maybe $20 for mac and cheese, pot roast, etc. The food was amazingly good and the servings more than substantial.
Have fun... we missed our week in NY this summer. We went last summer and were scheduled for this summer too as DD16 to takes a summer training program with the Rockettes. Unfortunately she severely sprained her ankle on 7/1, so no NYC, no dance, for her this summer. We are sad, but coping. It's hard to ground a dancer, but if the ankle doesn't heal well, it'll jeopardize roles in Nutcracker this fall, so.... it's turning into a long summer!