In my recent travels I went through Washington, Oregon, Idaho, Utah, New Mexico, Arizona and Nevada.
Prices were generally from just under $3/gal in Roswell, NM, to into the $4 range, up to about $4.29 at some places in Washington.
Generally, prices were between $3.17-3.89 in most places. I got fuel at a few places, Chevron, ONE9, Maverik and Sinclair. As I moved south, Chevron was generally at least 30 cents more than other places. Overall, car was running fine, didn't notice any major changes between suppliers.