High-Low

High-Low would be a game your wife won't ever complain spending money about, especially if you can hold your promise to play ONLY with it from now on and forget about the real casinos. It is one game that you can surely beat if you have good memory (or if you cheat). It can hardly turn you into the next millionaire gambler, but it can surely eat the time until the next airplane while keeping the real money in your pocket.