For 2007, I decided to use my car (as I'm wont to do now and again) as a makeshift camper, tightfisted scrooge that I am. (Mind you, I wasn't selling anything so keeping costs as low as possible made sense).
Where I slept, though, was fairly high ground, and flat - so really exposed to the elements, and I didn't get much sleep. I also forgot to bring my razor and a comb - and the latter would have been VERY useful given the high winds I went for a walk in that morning. Result: At the show I thought I probably looked a mess at best, hanging at worst, and when I saw the pictures after, they confirmed it.
So, for 2008, staying in the hotel might be a good plan. That way I can get pished the night before, since I won't have to drive the next morning, and look hanging for the actual show for an entirely different (but very good) reason.