Another vote for Spirit out of AC. (The AC Airport does have a website.) It's much smaller and easier to navigate, parking is much easier, and everyone we have ever encountered has been very friendly. I prefer to fly Spirit out of AC rather than another carrier out of Philadelphia.
I'm looking for airfare for May, and right now US Air out of Philadelphia is way less than Spirit, as is Southwest. I really hate to fly out of Philadelphia, but there's quite a difference in rates. I guess I'll just keep watching for now....