If you know exactly what you want then you should be okay booking the car here. Too many times, I've seen people be convinced into paying more for what they really need. Of course, they will always try to offer you an upgrade to give you more leg room. But if you're just driving the car for a day, probably not necessary. Or if you've already been in compact cars before and feels fine driving it then no reason upgrading. But definitely get what you need and spend the extra money on the trip! :)
For my particular experience they offered to upgrade my car but I chose not to. I can tell by the way her tone changed when I refused all of the add on that she was offering. In the end, the rep didn't even tell me that since they don't have any compact cars anymore she gave me a SUV. (If I had agreed to the upgrade cost I would've paid extra for something I wouldn't otherwise have to do). So know what you want, and get what you need people! :)
Also - Dropping off the car was rather quick and painless, that was probably the most pleasant experience. LOl