I've got to admit, the talk of crowds does give me considerable pause...nice to hear that they can be avoided. The 4X4'ing possibilities down there have me drooling a bit. ;)
Have a look at the trails on http://www.rr4w.com/
Then have a look at the ratings. Out mountain biking, especially during Jeep Week, I've seen units on some of the 7 - 10 trails. They are not kidding about rollovers. When one of them goes over, the others run out a fretwork of winch straps, and somebody starts giving the orders. In a minute, it topples back over into just the position it should have been in when it tried the problem. They are also, in the ratings, not kidding about required equipment, and about having some driving skills. When you meet them out on the rock, even if you are one of the self-reported good drivers that 90% of us claim to be, you will see skill you never imagined. Because I have to confess - they bring this up repeatedly - that I have low tolerance for body damage, and because I am clearly not the hotshit driver I thought I was, I am limited to class 4 or maybe on a good, lucky day, 5.
So, one possibility during the meet-up is a 4-wheeler SIG. Another is to gather some people and rent road lice (UTVs), or if there are doubts, do a group UTV trip with a paid guide. My swedish rels did this and were so excited and happy afterward that they could hardly settle down.
October is usually thought too late, but lots of times there is wonderful hot weather then, and a raft trip on the Daily section of the Colorado would be another possibility.