Rick covered it pretty good, so some of mine are the same:

1. Nicer the track and facility the better. Gravel sticks to slicks, and mud is bad
2. Camping and showers available
3. 75-80 Percent total purse payout of entry fees
4. Multiday event. Sat-Sun with an extra race and test on Fri, parking Thurs evening (5pm-12pm ?)
5. More than 2 classes. Such as Electronics, No Box, Footbrake, Sportsman (not ET defined but equipment, maybe an index or two (no electronics whatsoever).
6. Distance depends on gasoline costs, and that is very high right now.