Hot, windy, flat, and one of my few defeats on a bike. I did it around 2006 or 2007. I think they only had 12,000 riders that year.
I had a bottom bracket shell separate on my frame a few weeks before the event. At that time, De Rosa was renting bikes at the event for the event. I put one on reserve. When I got it, it was a tank compared to what I was used to and didn't fit me very well.
About Mile 50 I knew I was in serious trouble between the bike, the heat, and not eating enough. I slogged through the next 25 miles, but ended up flagging down a ride.
The heat can be your biggest enemy. Stay hydrated. With the groups, it's easy to fight the wind.
There are plenty of groups to get in. And if you find a snobbish one, drop out and grab another. There shouldn't be a lot, but with so many riders, there is always going to be some egos out.
It was well supported then, and I'm sure it's even more so now.
The hotels did book quick, and I recommend getting one ASAP. I have also heard lately that they are doing packages now, so you are forced to reserve the room for the entire weekend. Also, be aware that many hotels raise their rates for the ride weekend, so it might pay to do some shopping around.
Let me know if you have any other specific questions.