So not worth it unless I need to go to Costco anyway. But my wife will drive over there just to fill up sometimes. Weird.
The other funny thing is people driving miles past one gas station to another gas station to save 5 cents per gallon. It's one of those funny things we do as humans that we think makes a big difference, but it doesn't.
But in any case ... it's not true that there's always a Costco within easy reach anywhere in the Western U.S. At least I don't consider a 20 minute drive easy.