I had just googled "cowboy diner" and that was the best photo! Lee said it's pretty close to her, and that the steak and eggs are good (inexpensive too).
It's Davies' Chuck Wagon Diner on West Colfax Ave. in Lakewood, CO. The food is very good of its kind (I mean, it's diner food), and just inside the door is an antique barrister bookcase that is the envy of OCD and me. The diner folks use it to hold t-shirts.