The restaurant in the depot in Cheyenne is good. Jeffrey's Bistro in Laramie is excellent. Su Casa in Sinclair is also very good. Maxwell's in Cody is very good. CowFish in Lander is excellent. Old Yellowstone Garage in Jackson is top notch. If you drive through Metetessee, stop at the diner on Main Street (there is only one) and have a piece of pie. It is TO DIE FOR. An added bonus is that the juke box in the bar next door has 5 songs for a buck.
Unless you hit Chugwater during their summer festival, the chili isn't worth the stop.
Oliver's in Sheridan is absolutely outstanding! Matt, the chef-owner is a CIA alumnus who did time in France and New York and then returned to his roots in Sheridan to first open the Ciao Grille which morphed into Oliver's. Some northern Italian/Mediterranean influences but also fish and local beef specialties. Dynamite wines at reasonable prices. Highly recommended.