As someone who got into both of these schools, I will tell you why I did not even consider FIU over UCF for a second. (and also clear up some misconceptions that I believe you have about both schools).
FIU - I am a born and raised Miami-an and my parents work in the healthcare system here so I know about FIU. First of all, I highly doubt there will be any opportunity to get involved with UM research unless you personally know a researcher. Those spots are dedicated to UM med students. Secondly, the hospital affiliations for clinical training are basically the UM left-overs and opportunities at UCF are substantially better. (i.e. Leon = ****ty, Baptist = private and no opportunity for med students to work first hand, only Jackson north, etc. plus if you don't speak spanish I would be concerned) As far as Miami being fun, this is true BUT NOT WHERE FIU IS. FIU is in WEST KENDALL aka far and much more in the middle of nowhere than UCF's campus is. So if you wanna live somewhere fun you will constantly be commuting. Also, I'm not sure how much time you'll really have to go out. There match was good, I think UCF had a better match.
UCF - they do have graduate medical education, as well as at Florida hospital (and quickly expanding)
http://med.ucf.edu/academics/biomedical-program/graduate-programs/
The physicians in the community are EXTREMELY involved, during their neuro anatomy dissection they have local neurosurgeons coming to help etc. (not sure why you don't think they are). There are tons of research opportunities (they have a required research project so obviously you can do research) if you are interested in biomedical research they have the Burnett School of Biomedical Sciences. I am personally excited to move to Orlando from Miami because I think they have great shopping, lots of things to do, places to go out, lots of concerts, easy access to the beach, and overall more culture, AND DISNEY (Miami can get boring quickly). Orlando is big, just because the school isn't in the heart of it all I wouldn't worry.
My personal experiences on the interview days were:
FIU - extremely underwhelmed, seemed very unorganized, facilities were disappointing. I came away thinking, well if this is the only place I get in I'll be ok.
UCF - immediately became my first choice, blew me away, far more impressed than at FIU and was hoping to be accepted immediately. Attended second look which further affirmed my feelings and got me excited.
Bottom Line: I don't know why anyone would think FIU>UCF it would be hard to convince me of that lol. So if it were me it would be all about money. Full tuition is hard to say no to, granted Miami COL is more than Orlando so it may balance out. Go where you are happiest, if you are happy then you will thrive. If you are at a school where everyone seems not as smart as you and only got into one medical school, you might start developing a bitter feeling/complex.
Good luck deciding, maybe I'll see you in August?