I can help you with the SC colleges:
+ College of Charleston: liberal arts school; mid-sized (between 5000-10000 students), about 65% female I think. Lots of school spirit, and a very large greek system. Their campus is in the heart of Charleston and is absolutely gorgeous. I really love it there. They have solid programs in most majors, though I wouldn't say they have any one particular degree program that they're a national or even regional leader in. Overall I'd say it's a very good school. Something to be careful of, though, is that lots of students come to CofC and never leave because Charleston is so attractive, so the job market here is glutted with college graduates. It makes getting a professional-level, decent-paying job really difficult unless you have a technical or specialized degree like computer science. If you're majoring in psychology and want to stay in Charleston, you may as well resign yourself to clerical or administrative work.
+ Furman: good school with high standards, but not well-known outside of SC. They are a Baptist school and it's a very heavy influence throughout the University. They have a good football team with a good following and are in a good athletic conference, but I'm not sure they're competitive in anything other than football. I believe they're somewhat smaller than CofC though I don't know numbers. I don't know anything about their greek system. I do know it's VERY expensive to attend, and they're not exactly bursting with scholarship money (I got a free ride to several universities but the best Furman could offer me was half-tuition). I also seem to remember they have a strange way of scheduling their classes, though that might have changed in recent years. In summary, they're a strong school but very regional in focus.
+ Clemson: awesome, awesome school. I went to Clemson almost blindly--my parents were not from SC, nobody in my family attended there, nobody in my family was a Clemson athletics fan. I went to summer camp there in the 8th grade and that was the extent of my exposure. They gave me a free ride and recruited me the hardest, so I felt good about going there. I fell in love with it in less than a week. Clemson has incredible school spirit, especially when it comes to football and other sports. I've never been anywhere else where students were so proud to wear school colors on a near-daily basis. It also has a large and influential greek community. They're a medium-sized state university with about 17000 students overall--but one thing any student or alum will tell you is that it feels like a family no matter where you are on campus. Speaking of campus it's absolutely beautiful, one of the country's best. They have very strong and nationally-recognized programs in several majors. I don't know if their Psych program is ranked nationally, but I do know several people who were Psych majors and went on to have successful careers. Clemson Psych majors have a good rate of acceptance into Psych grad programs as well. The biggest knock on Clemson is that it's kind of in the middle of nowhere--it's a rural setting to be sure (though there are several small/medium cities within a 40-minute drive). That can take some getting used to.
I also know FSU is a gigantic school (I want to say 30K but that's a guess) with tremendous school spirit. They have a very strong athletic program and great academics as well. I've only seen small parts of their campus and it's very nice. Florida is beautiful (and hot) in general, although in my opinion Tallahassee itself is kind of a dump.
Best of luck in your decisions!