We go a bit the other way and just don't worry about how much time he plays. DS is 7 and DH is a gamer, my brother is a gamer and a web designer and my dad is a computer programmer. It's in his genes to be a gamer too :-) I also found that the more I try to control it, the worse his craving for it is. If I just leave it be with a basic "homework first" rule, he often chooses other things.
For games, we have Boom Blox and Boom Blox Bash Party, MySims Racing, Mario Kart, Mario Party, Super Mario Galaxy, Wii Fit, Wii Sports, all the Lego games and a few others. I don't let him play anything with guns or violence but the Lego games are so unrealistic that I don't worry about it. I also find the puzzle-solving requirements of the Lego games to be more challenging than most others.
The hardest puzzle game we've played is Zack and Wiki's quest. DH had to get cheat codes online because the logic puzzles were so hard in a few places!
We primarily play family games together and DS rarely plays Wii alone. He has his Nintendo DS for that.
As for the educational component, I have a reluctant reader who is self-taught and was purely inspired to learn by Pokemon games on the DS. I refused to read the directions to him- if he wanted to play he had to figure it out. He jumped 3 grade levels in reading in just about a month... I credit Pokemon :-)
