Good advice here. We've done all of them. One other thing we learned was that even a station with the pumps perpendicular to the building can be easily used IF it's one that caters to big rigs and they can drive all the way around the building or if it's on a corner with an exit to the road that runs along aside the station. We just get into the outside lane which allows us to either circle the building or veer to the side exit where we can make a couple of turns and re-enter the road we came in off of.
Best advice I can give you is if you're not comfortable with the set-up, don't stop there. We did once, because stations were few and far between and none had been RV friendly. We thought we were going to have to get out and unhitch the Jeep because of a car that had pulled into the place after we did and parked right in front of where we needed to go. Kept waiting for the driver to leave. When he didn't, I went in and learned it was the clerk's car. He said he wouldn't move it.
I went back out to tell my husband. Before we could even begin to unhitch, the guy hurried out with a change of heart. Maybe he noticed how much we'd just spent. Or maybe he heard me muttering something about contacting corporate headquarters and posting on the Internet as I left.