The road from the north (Alt 41), past Ft. Campbell, is lined with businesses for miles. Most of the businesses are on the east side, with the base taking up the west side of the road until closer to downtown. There are so many signs and businesses that you can barely find what you're looking for. There are army surplus stores, tire stores, scary taverns with no windows, strip clubs, and restaurants: Korean, Vietnamese, Japanese (sushi and steak house), Thai, Mexican, fast food, pizza, an American steak house and more.
Most of the restaurants are independently owned and have varying degrees of cleanliness and "yumminess." We found New Korea and Yamoto Japanese Steakhouse (good sushi too) to be good, but we also tried some other places with mixed results. If you are not an adventurous eater, I would steer you toward downtown and to the chains off Exit 4, near the mall. Otherwise, pick a place and dig in.
Quick Tips:
Charlies, The cinderblock steakhouse with the big steer near gate 7 has a good reputation with the locals.
Best Way To Get Around:
Driving seems to be the only option. This town is decidedly not bicycle-friendly. There is a nice walking/ jogging path near the river.