Don't know about other airline partners, but AA Pt (probably ExPt and maybe Au also) get 500 bonus miles every month if dine at 3 or more participating restaurants.

So aside from restaurants appropriate for business meals, I also like inexpensive fast food places to top off if I don't have 3 in a month. In the SJC area, I can get a taco from one of the Una Mas chain for under $2 for an extra 500 miles.