COTA is nice, but the settled rate at $55k a day is ridiculous. Personally, I don't like to be at a track for any less than 2 days because it's really hard to get any feel at all for a track unless you're there that long. Especially with a big group with large gaps between sessions. At $110k for a two day rental, you could rent Miller Motorsports Park for a week, or most of the race tracks in the US for a month. With the way the values of the cars have risen, and the subsequent decline in interest in even 7/10ths driving, might be a tough sell.
It is a spectacular setting though.