When I worked at Vanderbilt, Provence Breads & Cafe was one of my favorite lunchtime haunts. Their freshly baked breads are phenomenal, which makes any sandwich great. They have a great selection, and all of them that I have tried have been delicious. Their prices are about average for what you'd pay at a deli/cafe in the area. It also has kind of that European cafe feel, which is nice to find in the middle of Nashville. It can be crowded on weekdays at lunchtime, and parking can be a big hassle if you aren't already in the Vanderbilt vicinity.