We have thought about a Castlevania marathon and may do one in the future. We love those games and it would be awesome to do.
We would probably like to do longer marathons, but since there is only 3 of us and we all have full time jobs taking the time off of work for a marathon isn't always feasible for us. Even if 1 or 2 of us could do the extra hours it's not the same when the whole team isn't there. I'm glad to hear that you enjoy our marathons though!!!
Not many people do Starfox which could be fun. I'm not sure if Starfox Adventures would be fun to play/watch. I dont think I've seen you guys play Mario which would be cool. If we could time it well, then GenGAME could do a collaborative marathon if the stars align themselves and the schedules match up perfectly. The last marathon we did was a "Best of Nintendo" marathon which was a blast. We played Super Mario World, Sunshine, Galaxy 2, Twilight Princess, Luigi's Mansion, Star Fox 64, and a bunch of other games. It would be cool if you guys did a bunch of Nintendo games.
I know you guys have a lot of retro games too. Maybe play some of the cult following games that maybe a lot of people haven't heard of. (Not sure if this would bring in a big crowd though.) I've also tried to get GenGAME to do a 007 marathon, a Medal of Honor marathon, Capcom marathon, and Star Wars marathon. I'll convince everyone they're good ideas some day!
No, Matt's really the only one with any experience in those games and he has mentioned a marathon for that series. I would probably do it, but I'd have to train in them a little to get some idea how to play them.