I went once when it was in Milwaukee and my wife and I have been every year since it moved to Indy. I usually end up spending the bulk of my time with the folks from Necromancer Games. Last year I ended up running a lot of pick up games/demos using my Shades of Gray adventure from Necro.
If you're looking for older edition games, you can find some, but you may have to look for a lot of pick up games not official events. If you're looking for older products, you can find a lot. Titan Games, Troll and Toad, and Crazy Igor's all have a vast selection of older stuff, and lots of other vendors have boits and pieces. Of course, you can always spend time at Frank Metzer's auction where he and luminaries like Tom Wham and others regale the crowd with stories of the old days at TSR and sell all kinds of game stuff, including a lot of 1E and OD&D materials. Two years ago this included the original cover art from Gods, Demigods, & Heroes, and last year had one of Gary ms of Temple of Elemental Evil, so you get to see an exhibit of cool pieces of D&D history even if you aren't bidding. So, the older stuff is there if you are looking for it. Frank also has an auction store with a lot of older material. Check with Frank's crew what their schedule is though, as sometimes it focuses on board games, miniaturs, and CCG's. Col. Lou Zocchi usually has a booth somewhere there as well with a lot of Game Science stuff, and usually has a decent selection of older edition stuff there as well, plus lots of old school dice,
One hint, if there are people from message boards you want to meet up with, definitely exchange cell numbers before hand and establish a place/time to meet up and play/ socialize, etc. The con is also a great time to try new games for free, as lots of demos are available in the dealer's area and you can try lots of things. COme witha spending budget and don't blow it the first day. You can definitely spend too much very quickly if you are not careful (especially at Frank's auction).
-M
