USC really sold me with their admit day. They've been really good at sending me stuff once I was admitted. Before that though, I didn't have much of an idea what they were about. They sort of pissed me off early in the cycle by returning my application to me because I had accidentally failed to check a box that they could have easily looked up (the one about having applied to USC before). That's a pretty petty concern though, so USC gets a definite thumbs up.
Michigan has been amazing. They're nice when you contact them, they respond promptly to e-mails, they provide WAY more information than other schools in a down-to-earth FAQ. They really go out of their way to give a good feeling about the school. I would have been sold on Michigan even without this, but I think it may have been a not insignificant part in convincing me that I'd be willing to wait a year if I could get in.
William and Mary was very nice, and they went out of their way to give me contact with current students and that sort of thing. In the end, it just didn't feel like a great fit for me.
i'm not sure i really have enough contact with the other offices to give much of an opinion. (see Emory and Texas for my negative reactions).