It really depends on my mood. If I'm getting in a few quick games, it is only one pin. However, some nights I like to just setup in my basement. And if I'm going to be in there for a couple / few hours, I'm turning it all on. The games, the crown molding lights, the background lights, the slot machine, the arcade consoles, the TV (tuned to some sports). Everything.
I suppose it is a waste of electricity. But I'm always happy at the end of those nights. On nights like that I'm not concentrating on high scores, I'm just relaxing, playing pins, watching some sports, having a glass of wine, and just enjoying my little arcade.