Yeah, I have a few friends that go. I might be able to get some video game soundtracks there, but it probably doesn't get any closer to actual game music concerts than that. Ah well. I take it you are not Mormon just as I'm not, correct?
There is Anime Banzai. I think it started a few years ago. This years is October 8-10, in the Davis Conference Center in Layton. According to Wikipedia, last year about 3000 people attended. Looks like it covers anime, gaming (digital, card, and table top), panels, cosplay, etc.