07 Fisher Paragon, 00' Lemond Buenos Aries, Specialized Langster, Schwinn World Sport SS townie, 99 SS-Works single speed conversion, early 90s Raleigh roadie rain bike, 07 Fisher Rig, Trek 520, and a home-modified chopper
I grew up in the Phoenix area and rode in lots of sand. I would agree with all of the above except for 7. Once you're in the sand and fall over it's not so bad. You can, however, get really hurt entering the sand if you bury the front wheel causing horrible endos.
Some things I've learned when riding in sand:
1. Steer with your hips more than your arms.
2. Keep your weight back so as not to bury the front wheel.
3. Pick a gear or two lower and keep a fast cadence (90-100, at least).
4. Stay loose, it's usually better to let the bike wander a little than to force it to a narrow path.
Theres a stretch of trail here by a creek that is all sandy, Not nearly as bad as you guys probably, But I've learned that steering with your hips is definitely a better turning technique.
I've also learned that fighting the bike in sand isn't going to help much, best to let it wonder a little bit.
Basically, I just repeated something someone already said...
I left off a couple of items and have noticed that while on my single speed I can do as well or better than on my multispeed. That is to keep a steady cadence, work on balance practice just standing without moving, and to look up often to pick a good line that you can get to with a slow adjustment rather than a fast one.