Running into this problem, too. The best approach I've found is to try and get through one at a time, based on what kind of mood I'm in. If I start something that I know is going to take awhile (Tales of Xillia being the current one), I'll usually keep one or two things on standby for when I don't feel like any big time committment or just need a change of pace, like a fighting game or RTS.
The biggest problem just comes down to not enough free time. I'm lucky if I get three hours in on a weeknight