If you look around at the many Indy GT events across the country, one thing that you will see in all of the ones that have had a good run of years is local participation. At Patriot 2010, about half of the players were local. That's awesome. The more local gamers that come out to events, the more folks that will come from non local areas. Gamers love to go to large events. More players, more chances of doing things that gamers do with folks that you've yet to meet!
Warhammer and Warhammer 40K are really fun to play in the tournament setting, mainly because most of the players know that they are getting in 3 or 5 games against opponents that they don't usually have the opportunity to play against on a regular basis.
If you watched the past Patriot Games closely, you saw that over 2/3 of the field were playing folks not from their gaming group throughout the event. The top scores had to match up against each other, but that's logistics. The average player at Patriot played at least 4 games against a player that he had never played against. The average player made at least 3 new friends, and that's more than some of make in years. The average player at Patriot played through unimaginable heat, but perservered without so much as a loud scream! The average player is what makes any event run well, and as an event organizer, I gear all of my events around the average player, you know, the guy that likes a good burger, some cold beer, a fun atmosphere to play in, some awesome scenery on the game board, an opponent that laughs at his corny jokes, a chair at the table, and a good time!
That's my formula for a successful event.