Shelter fabric on the playa is a set of compromises. To hold up against strong winds, you want it to let the wind through, but that makes it less waterproof in case it rains (which it's done too often the last few years). Too waterproof and it catches a lot of wind, stressing your supports and tearing the fabric if it's not up to the constant battering. You need strong fabric with good anchor points, but you don't want to spend a ton of money on it (or I don't, at least).
I started out with Sarlon Polyshade brand knitted shade cloth (many others, like Coolaroo, are available; the best are the knitted kinds that won't unravel), which is an incredibly strong, light knit plastic cloth sold at places like Home Depot. It comes in a multitude of colors, including playa tan and light violet, and stops 80% of the sun (other densities are available, too). It's a bit expensive, but it's lasted me for 5 years of annual playa exposure with no signs of deterioration. It's nearly impossible to tear, and cable ties slip right into the weave. Because it's knit, the holes for the cable ties don't grow or stretch, even under the most aggressive winds. Sarlon comes in 6'x24' rolls (as well as others), which I originally cut in half for 2 6x12' pieces. If I did it today, I'd keep it full length, since my shelter has grown since those days. I stretched these across the PVC frame and used cable ties to hold it tightly to the frame. This leaves about 2' of excess at the end, which can provide extra sun protection at the opening, or can bridge the gap to another structure. This worked pretty well during the middle of the day, but had some problems in my original design. One was no sun protection in the morning and evening; it wasn't really hot, but the sun was in my eyes. Another was that the 80% shade still let too much sun through on really hot, bright afternoons. Also, the wind protection was minimal, between the gaps and the loose weave.
I obviously needed better coverage, but I didn't want to buy twice as much shade cloth, so I went to the fabric store and got a couple of 7 yard pieces of playa colored fabric, one a stretchy knit, the other an unstretchy weave. Fabric comes in a variety of widths, and these were 60", the widest typically available. On the discount table at $1.30/yard, they cost about $10 each. Normally, I'd be worried about these fabrics on the playa, because the first big windstorm would rip them to shreds, so I put the Sarlon on as usual, then stretched the cloth fabrics across it. I snipped holes in them every foot and used cable ties to tie them to the PVC. The Sarlon provided excellent support, preventing the cloth from tearing in high winds, and the cloth cut the sun and wind completely, covering the frame from playa to playa. This has worked well for 2 years, though 2 tie points at the bottom tore this year. It still held fine, though.
One of the problems with this structure is that it takes a lot of time to attach the pieces of fabric to the frame, so my main planned improvement is to make the pairs of shade cloth into single pieces, possibly with pre-fab loops that I can slide the PVC into. I'll test it in the back yard this year and take pictures if it works out.
You can get surplus Desert Storm shade cloth from Twin City Surplus in Reno, who have great big pieces available as I write this. The web site offers 12' wide rolls at $13/yard, but theirs was a big 20x20' square for about $200, which would cover a double-length quonset in one big honking piece. It's 90% shade (which made very effective shade at BM2K). The only drawback is that it's woven, not knit, so the cut edges need to be taped or folded/rolled over to prevent unraveling, and it's not as strong or stretch-proof as knit cloth at the tie-down points. I'm contemplating buying a big piece if my improvements don't work out.
There's a lot of info on shade cloth at Discount Shade, who are unfortunately (for those of us who'd like to buy from them) in Australia.
I've not tried parachutes, but I know the fabric is strong and water-resistant, and it can be economical if you find the right deal.
Here's the Sarlon shade cloth before the fabric covering:
And here's what it looks like with fabric over it:
