We managed to find a Whole Foods Market in every city we stopped at overnight--Cleveland, OH, Omaha, NE and Park City, UT. In fact, the Whole Foods in Cleveland and Omaha were super-sized. In Park City the Whole Foods was literally right next door to the Holiday Inn we were staying at.
Whole Foods has all kinds of high-quality prepared foods and salads. So, we were able to stock up and have food for breakfast lunch and dinner all 4 days (eliminating the need to stop!). I would definitely recommend checking out the list of stores on the Whole Foods website, before planning a trip like this.
Even though time was of the essence we did manage to make a quick pit stop in Cheyenne, Wyoming to buy some Western Wear at The Wrangler. Housed in a big red brick building just off the freeway it's hard to miss. Great selection of western shirts, boots and hats.
1518 Capitol Ave
Cheyenne, WY 82001
At some point I would love to go back to Cheyenne for Frontier Days (July 18-26 2009) which is huge rodeo event there.