1. "Theme" nights- Play certain games certain nights, so that the Quakers can come Monday knowing other Quakers will be there, Tuesdays for Tribes, ect. The "theme" referees would also go well.
1a. Don't set a permanent game for Friday night, all of saturday, or daylight sunday. Those are "free" times for many people, and having a rotating game list(quake sat, Diablo sun, tribes next sat, ect) can help.
2. Some sort of voice communication system(for team games such as tribes) BYOM(bring your own mic) would be a good idea for this.
3. Food- Make sure you have lots of soda(especially Dr. Pepper), chips, ect. Junk food and games are synominous in my head.
4. Location- While not much can be done about this, try to be near neighborhoods. Younger gamers(aka those of us without cars) can't easily make it if it's downtown(though it might not be as much of a problem in portland, since TriMet runs til midnight, or so I belive).
5. Make sure you have a good mouse, most people won't settle for anything less than an Intelimouse(the ability to bring a mouse would be nice too, but probably not feesable).
6. Make eyeScreem(or other brand of steroscopic glasses) availible for renting. Since people will only be playing for an hour or 2, they probably won't get any headaches, and will be glad to use them.
7. Make the lobby fun. Keep some pinball and older video games in there(for the change in pace). Also, have some good techno music going, so that people not playing can still have some fun.
8. Make the seats large and comfortable. Not all of us geeks are small, so make sure you don't plan on seating a "small" guy.
9. Keep strict rules about how people act. If you have problems with people getting out of hand, it'll destroy the gaming environment, and drive away customers.
10. Partitions are a good idea, but not nesscary unless it's a RTS game, or something of the sort(where stealth and/or secrative planning matter).
11. Make a good website. Like NexGen, if you have a setup with a webcam, and a list of who's currently playing, you may be able to get people to come on down if they see that their frind is playing.
12. Mods- Make sure you have a good selction of mods availible for games. Nothing like a good round of Jailbreak will get people going.
13. Keep the building cool. Many people will have a hard time gaming if they're too warm.
14. Go for good machines, but not the best. A GF1/Athlon 700 is a perfectly good gaming machine in my book, and the savings can be passed on to the consumer.
15. Prices- Offer varible prices depending on the game. Some game types take longer to get a good game out of, and a lower price will help attact the players of those games. On the flip side, most people are content with an hour or so of Quake, so charge them a bit more. Also, offer "specials" on brand new games. If people don't have the game yet, they're prone to stay and play for a long time.
16. Nerf anyone?