Signs. Obviously we needed tons and tons of signs so people could find the place.
As to the actual event itself, overall I was very happy with it. However, that's not terribly useful feedback, so in the interest of providing feedback, I'm going to be bit picky here. Take it with a grain of salt, because they're really not complaints, I enjoyed it!
My least favorite was the mini-airhockey tables. This may just be because I have a deep love of airhockey, but it was _very_ difficult to play on those tables. And I don't mean "have a serious game" I just mean casually play. The small table was a minor problem, the pucks getting stuck under the mid-court things, and teeny-tiny um, thing you hold to hit the puck.. was really hard to hold. I heard this from the 2 other people I know who tried as well.
Laser tag would have been significantly better without all the mirrors. I'm fairly certain just pointing at random surfaces was enough to kill people. The quality of the laser tag system, was admittedly a bit low, but I think that's not unreasonable for portable laser tag. This was frustrating for several people.
I didn't play the Wii setup, but heard good things.
Overall, I would call it a huge success and I had a lot of fun. I look forward to what happens when you have more than 2 weeks to prepare. :)