Cash. Miles are being slowly devalued, either explicitly (i.e. AA and CO raising mileage award levels) or implicitly (i.e. possible liquidation of your miles in UA chapter 7). Assuming a $50 meal, you get $7.50 cash with the 15% rebate, or 500 miles (worth $7.50 @ 1.5 cents/mi.) I don't go out of my way to dine at these places (most of which are hurting in my town), so I won't receive any bonuses based on monthly usage.