I have used gas cards exclusively to pay for our gas the last couple of trips. Coming through Illinois we have found Shell to be about every exit. Shell is also in Southern Georgia and Florida but not as frequent in Tenn and Kty. We used BP in Kty and Citgo or Exxon in Tenn and Georgia. Exxon is also the on property gas stations at WDW -- a little expensive but we have found it worth it to have one Exxon card to fill up there before we leave for home.
Liz