I've got to say, Mario Kart would have come up on my list eventually. Personally my situation is a bit different though; my wife beats me at Tekken and i beat her at Street Fighter, Soul Calibur, KOF, etc. needless to say we find common ground and equal playing field on Smash Bros Melee. Mario Kart 64 is the best of the series, hands down, and if you can get past the Playskool-esque controller you'll have tons of fun with it. my original suggestion when reading this question would have been Tetris. there are enough variations and enough different version that whatever existing console you have, you'll likely find an inexpensive solution in a tetris-like game. my parents have been playing tetris attack against each other for the past 10 years at least, and one is clearly way better. check out Fantavision, Devil Dice, Q*Bert, etc. puzzle games don't require as much 'gamer's skill' as they do thinking skills to get good at.