The first time I visited FSU, it was during winter break. There's not a soul on campus (except in the bookstore) and everything is closed.
I was able to tell the campus was nice and all and even able to get inside Doak which was impressive to me, but I would recommend making your first visit during one of the previews where you can take a tour, see what the campus looks like on a school day, and check out some of the residence halls. I believe you have until May 1 to send your deposit, and the previews are well before then. You'll get information on it with your acceptance though.