I generally find that I like to play games that you can play for a little while at a time and stop whenever,
like Halo 3 and UT3 multiplayer, Wii Fit (just started it up again), or Virtua Fighter 5. Sometimes I'll play stuff like Mass Effect, but usually I play longer, more involved games on days off if I have time. And then I'll also usually play a handheld game before I go to sleep. Phoenix Wright 3 is ever-so-close to completion now.
But there's plenty of days (or weeks) when I won't touch anything on weekdays. Just too pooped from work and I just sorta veg out watching TV shows, movies, or internets.