Sometimes just laying out the fixings for a good salad bar makes the teachers very happy...like a ruby tuesday salad bar for instance. I've done that for PTO get togethers at my house and the women (usually watching their weight) love it.
We used Subway last spring for a teacher appreciation lunch and they sent a TON of food. They sent us 3 tray of various 6 inch single meat sandwiches and separate containers with all the fixings. There was so much lettuce and veggies left over some of the teachers used them to make salads the next day!