I use a 5x9 tarp i made. Setup depends heavily on conditions. For rain, the A-frame works best IMO. I have about 8" or so of line between the tarp and the stakes on the corners. It's not too claustrophobic. I like the lean to when I have a fire or if its nice out. there are a lot of great ideas for tarp setups at equipped.com/tarp-shelters.htm
I tried the forrester setup he shows. Its great for ease of setup, and not too bad weather resistance.
If i stumbled over 30 yards of silnylon, I would make a 5x9 poncho for solo (8' is too short for comfort for me, being 6'2). then I would make a 9x10 tarp for 2-3 or 4 people (spooning?). Then, I would sell the other 20 yards of material to me for really cheap. Ground sheets, VB bags, packs, stuff sacks, water bags, etc. would also be cool to make if you dont I guess.
Good luck with your new find.