Junior's right in the heart of the theatre district is a perfect spot to eat before or after your show. I eat there pretty much every day when I go to NYC, and I get to NYC about 2-3 times a year. Was just in NYC 2 months ago for 2 weeks, and ate there every evening. They have a very extensive menu and the food is always delicious.
With it being right in the heart of the theatre district, you can get there early, have nice relaxing dinner, or lunch and get to the show without being rushed. Just allow for time as it can get quite crowded right before or after a show. Now that it's summer, the outdoor patio is a great spot to eat at.
Junior's just opened up it's 2nd midtown location on Broadway.