[You’ll get 20 percent from me for excellent, personal service and would have to have done something extraordinary to get more than that. Competent but unremarkable service gets 15 percent.]
Pretty much my scoring, too. Though, these days, when I’m fortunate to dine out, I usually wind up at fast food to save.
There actually are a few sit down country diner sorts of places around here that are fairly decent and as cheap as fast food inclusive of tip so I try to go there when I can, their breakfast is usually the most appealing.