as for 1/18th scale, there are not many racing them anymore (which is a bummer because I love my RC18b) Nearly all racing is 10th scale. There is a group of guys that practice on Thursday with them however.
Speaking of DEAD racing, the 1/10th NITRO truck class in Vegas is a joke. The outdoor tracks around here, and in lots of places are so geared for 1/8th scale Truggies that the deep ruts make it a total minefield. Finishline is like this, but is fun to run truggy. The Silverbowl track is a bit of a joke when racing is not taking place, as it gets blown out and dry with too many silly obstacles and insane launches. There is another track nearby (less than two blocks from my house) called Sin City R/C which is built literally in a backyard. I have yet to make it out to see this track, as it is invitation only and you have to call someone to get directions, however I am told it is fun.
Also on Fridays there are a group of the on road guys who race on the carpet, 19t sedan and 12th scale which is regaining popularity here after the IIC was held in vegas this year.
A group of us will be heading down to So Cal on Friday for the last race. Hopefully more really good facilities open up in Southern California as well, its nice to have a good place to race 10-15 minutes drive from you.