I like the coffee shop in the Hilton. Convenience trumps gastronomy. You can park in the lot, enter the lobby (level 2) without going outside, then go on the enclosed ramp to the arena without going outside again. Car to courtside with a roof constantly overhead. And the food and service and ambience are acceptable if not unforgettable.
Max Bibo's on Trumbull Street (across from the XL Center) has good light fare (sandwiches, salads, soups). However, the tables are upstairs, so you have to be able to cart your tray of food up one flight if you're planning to eat in.