So I just booked my rental car. Apparently all of the companies play a little game. If I booked the car Thursday - Sunday, the price was $15 a day. If I started the rental on Wednesday, the price jumped to $68 a day. I called, and there was no way to adjust the price.
So, I created 2 separate bookings. One for Wednesday, returning Thursday morning, and one Thursday - Sunday evening. The first day costs as much as all the other days combined. Worst case scenario, though, I just have to drive back to the airport and get another car. Not a big deal.
Just wanted to give you folks a heads up.