You've somehow managed to get tickets to VaporCon, and arrived ready to play some D&D!
Unfortunately, all the 4th edition games are filled up, because it's just so popular. There are, however, openings for games that use the rules to these other editions: 0e, Basic (B/X & BECMI), AD&D 1, AD&D 2, 3E, 3.5E, and 5E.
Which game do you join?
As I've said in the past, D&D has dungeons design (tight gritty resource management dungeon crawling, as seen in most of the old school crawls) and dragons design (larger than life high action pulp, as seen in Dragonlance and most adventure paths).
4e is awesome at dragons games (and better IMO for playing Pathfinder APs than Pathfinder itself is - including less prep time even including translating the system used). It sucks at dungeons games. Basic is focussed on Dungeons design.