Floating row covers like remay don't need any support other than what the plants provide. This works well for plants like broccoli.

I use 10' PVC pipes to span my 4 foot bed, creating a roughly 5 foot arch. Then I cover with 4 mil plastic. Keeps the frost off, but an experiment I did last fall showed no discernable temperature difference inside and outside my hoop covers.

Good luck with the various options out there.

Here is a link that might be useful: Sinfonian's garden adventure

Kam
Check www.totallytomatoes.com. I purchased from them based on a very successful gardener in the Portland are. She has successfully used hers for many years.
Jim

Peaceful valley organic supply has a good price on reemay or remmay-like product also. BTW, if you live in a windy area you may want something to keep the cover off your plants as it can shake in the wind and smash the heck out of tender seedlings and new growth. We used cut pieces (about 10" long) of pvc stuck into the ground and then heavy wire cut to make hoops. Then we just threw the cover over the hoops, cut the cover to length and attached it to the pvc, near ground level. To attach the cover you can use the special clips made for that purpose (sometimes hard to get on/off and expensive) or you can try really big binder clips from an office store. They're much cheaper and only leave a small rusty spot at the edge of the cover after many month's use in wet weather.