Union grill is on S. Craig St. very near CMU. It's a great place for a group dinner, with some larger tables. I've come here for an end-of-the-semester dinner with a bunch of friends, and also with a large number of family members. Service is typically friendly and fast.
Food is American, with large portions. Nothing exciting or special, but nothing to complain about. Satisfying waffle fries! Burgers are good. If you come with a group, the nachos are pretty big and good for sharing. Also fun s'mores dessert.