I'm in a city-owned T-hangar at GYR. There is only one FBO on the field, Lux-Air. They're good people, and though they cater to a lot of executive and corporate aircraft, they treat us bugsmashers just fine.
As far as I know there is no ramp fee. There is no remote or self-service fuel; all fuel on the airport is from Lux-Air's trucks. Also, there is no maintenance facility for light piston aircraft on the field.
If they're not busy and you're just coming in for a few minutes for fuel, you can often park right in front of Lux-Air's door. If they're busy or they expect a large aircraft in soon, they may point you to park a few hundred feet away on the transient line in front of the airport admin building, and someone will come out to you.
If you don't need fuel, just park on the transient line in front of the admin building.
GYR is the closest airport to the raceway, so if you arrive on NASCAR weekend (first weekend in November this year), all bets are off. The ramps will be crammed with Billy-Bob jets, you'll have to park two zipcodes away, and Lux-Air's staff will be swamped, so service will be delayed.