Thanks for posting this--I searched and searched for the "What Worked, What Didn't" thread and couldn't find it. Here's what we did that worked:
1). Keeping the car A/C on "recirc" while we waited in line to get in (~3 hours). There was a tiny bit of dust when we turned on the A/C after leaving, but only for a couple of minutes.
2). UGG-type boots (fakes from eBay, but real sheepskin). Kept my feet cool and comfy all week. You CANNOT get a blister from UGGs, no matter how hard you try. No Playa foot problems, either.
3). 18" wrought iron tent stakes, made from 1/2" iron stock. (Helps to have a blacksmith friend). No rebar for us, these worked great!
4). Large misting bottles for water later in the week when it got hot. I pretty much misted myself & anyone in my general vicinity who wanted it continuously until it cooled off at about 5. Neutrogena spray sunscreen, too. We went through 4 or 5 cans.
5). El-wire jackets at night & tons of blinkies and LEDs. We couldn't believe how many people were NOT lit, whether walking or on bikes. Dumbasses.
6). Showering every afternoon. We brought our own shower tent and found we could wash our hair and then use a washcloth to get sunscreen and Playa off for 1/2 gallon/person. Next time: less water. Once the sunscreen is off, the dust doesn't stick to your skin. We felt clean until we had to sunscreen up again the next morning!
7). Dry ice. We froze jugs of water and had 2 large coolers full. Each day, we'd move a gallon into a small cooler to keep other food, beer, and drinks cool. We gifted several still-frozen gallons when we left on Saturday.
. 2-gallon ziploc bags. We put ALL of our clothes/costumes in these to keep the dust off, and we can use them to store stuff until next time. Laptops, too.
9). Spare car & trailer tires. We blew a trailer tire on the way to BRC and were glad to have a spare (had to buy another one at WalMart so we still had one). Hydraulic jack, too. And major toolkit. You just never know...
Big wastes of time:
-- Car cover. Never even took it out. We kept having to get stuff out of the car. Just not worth the bother.
-- Aluminet. We brought this to shade our Gypsy wagon/RV, but never bothered to put it up since it was cool early in the week. Guess we could have put it over our daughter's shade structure (over her tent), but didn't think of it...