Personally, I believe everyone should bring their own regular lawn chair for sitting in camp, and also, a low-back (beach-type) chair for the tarp, depending on where they want to sit. It is always easier (and cheaper) to get these kind of LOW (beach-type) chairs from Wal-Mart or Target in May or June. There's a Wal-Mart in Durango, if you're arriving through that route.
I always bring a low chair that has my last name printed on the back with Magic Marker to use on the tarp because it's much easier to find in the crowd that way, when I'm walking back though the crowd with my hands full of beers.
I also prefer a low chair for the tarp because my tarp is always placed well in front of the dirt path that circles around and divides the two areas of the festival ground.
The historical rule is that ONLY low-back (beach-type) chairs can be used in front of the dirt path, because obviously, the people who sit behind you want to see the performers on the stage, also, and not everyone stands and dances all day and night. Also, we like to eat, drink, visit with friends, and read while we are on the tarps watching and listening to music while sitting in our chairs.
My chair has backpack straps and a pouch built in to carry my rain gear, lap blanket, etc. So, in addition to a regular backpack for other essentials, I am all set for whatever weather happens during the day and night on the tarp, and I highly recommend that type of chair to use on the tarp.
As far as sitting in other people's chairs goes, yeah, that's ok as long as they don't mind, or are not actually there on the tarp when you are there. If they return to the tarp and indicate that you are sitting in their chair, you should politely get up and let them have their chair again. If you want to sit and visit with others for an extended period of time during the day, it is most polite to bring your own chair with you. A chair with backpack straps is most convenient for that purpose.
Exceptions are made for those who have to fly in. Often, there are spare chairs supplied by camp organizers for those who flew in and have no tarp or chair. Arrangements to use other people's gear should be made well ahead of time though and no one should simply "expect" to have these things "provided"for them by someone else without making sure about it in advance. Many of us drive to the festival in our own cars and that is the best way to bring in necessary equipment and supplies. So, if you're driving, you should be able to get a set of chairs (standard and low)and bring them with you. As someone said earlier, buying anything in the town of Telluride is definitely going to be over-priced, if it's even still available, so don't wait until you get here to get essential supplies, if you can.
Listening to:
Andrew Allen "Loving You Tonight"
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