My Artic Mini has no admin buttons inside or at. There is one shift available admin function on the panel (player one start, down exits). Everything else is done via keyboard inside the cabinet. Of course every title on this thing was set up manually when I put it together, so there is no admin work at all to be done other than shutting down the cabinet, which I can do on the keyboard inside without even having to look.
My Amazing Mame has two admin buttons inside the coin door (pause and tab), and also has a remote control that can credit, exit, check framerate, and throttle. You can also credit it by putting in quarters.
My Tournament Mame (Dynamo Solitaire cabinet) currently doesn't have enough buttons to do anything besides play games, you can't even credit it without the keyboard (will be changing that). I usually just run games on free play, and have button one dual mapped to player one start and button one. Thinking about redoing this one with a vertical monitor anyway. All the good trackball games are vertical.
Mame Firebird has the coin reject buttons modded to be credit and exit respectively, and it has no other admin buttons. I think I set up a shift sequence for tab, but I can't remember what in the world it was.