In general,
1AB is the "Anime Fighter" room like King of Fighters, BlazBlu, Guilty Gear, etc.;
3AB is the "2D Fighter" room such as Street Fighter and Marvel;
4/5 is the arcade and charity event area typically with Super Street Fighter II Turbo or Xmen vs Street Fighter;
6AB is Mortal Kombat and MAME area;
7AB is "3D Fighter" room such as Tekken, Soul Calibur and DOA.
The registration booth is right in front of 3AB with t-shirts available on the other side of 3AB's entrance.
Keep in mind that it can get really crowded at the event. It's best to hang around the room for which the tournament you entered is in progress so you don't get disqualified for absence when your match comes up. If you're leaving the room during your tournament please tell the tournament organizer that you are stepping out for a reason (Play another match, bathroom, food, etc.).
For those that want to find me and chill, I'll be the tall guy in the cowboy hat.
The DOA event will be on PlayStation 3 by the way. There will be at least 4 or up to 6 stations for play.