Experience from a volunteer
I've swept the 66 mile race for the past three years. Every year, I'm amazed at the professionalism, coordination, and overall class of the operation.
That said, there are some spots where you can get lost. This is nearly unavoidable in a route network this complex -- realize that the 66 miler is just one of several events happening concurrently. There are intersections through which four or five different routes will pass. Unfortunately there can't be volunteers and ambassadors at every turn. I know exactly where people lose themselves, and I've done it myself: It's a dogleg on the Los Burros section of the trail, right where the trail heads up a valley.
Attitude is extremely laid-back, even for the guys at the front. The 66 miler racers who podium are so, so far beyond everyone else out there that you really won't see them after the first hour or so. The scene at home base is very cool and laid back, zillions of racers and bikes and families wandering around. Like a non-corporate, ******* version of the 24HitOP vibe.
The 66er is a difficult event. The trail itself isn't hard, but the accumulated effect is what breaks people: The altitude, the time, the sun, a handful of sketchy sections. I strongly recommend taking your breaks at the aid stations.
The 52 is a very nice version of the event. My first year, as a non-volunteer, I pooped out at the decision gate to hit Land of the Pioneers, so I followed the 52 back to base.
My understanding of the shorter events (41, 35, etc.) is that they're largely on the dirt road network up there. There's not a ton of singletrack on those events, mostly to keep traffic congestion down.
Anyway, it's a super-cool event and I'm looking forward to seeing more people up there this year. Probably volunteering again, although last year race coordinator Dave Mathews (who has never actually ridden his entire 66er in one shot) and I promised each other we'd actually race this year. Hopefully there will be a singlespeed category -- is there? I haven't looked at the registration material. So we'll see.
p.