Well I live in Jacksonville currently and have been in Miami, Orlando, and Tallahassee for extended periods and I can tell you that, like every state, it has its individual pros and cons and every city is a little different.
My home town, Jacksonville, is probably the most boring city in the state. Our businesses are spread all across the city so our downtown isn't a conglomeration of of people and doesn't have the same hustle and bustle as most cities. The crime rate gets pretty bad in some areas and a lot of people in general are pretty rude if they don't know you depending what part of the city you're in. We have a beach but it's pretty crappy and in general there isn't a lot of fun things to do in the city. The best thing I can probably say is that it's a pretty routine city with not a lot of surprises, so it's a reasonably decent place to settle down in if you're not the ambitious type. It's a bit of a college city with 3 colleges being here (University of Florida, Florida State College of Jacksonville, and Edward Waters College) as well as Florida/Georgia games being played here at our Jacksonville Jaguars' football stadium. Speaking of the Jaguars, they suck, so our sports morale is pretty low. That said, in terms of college cities, Jacksonville doesn't touch Tallahassee or Miami. Best thing I could probably say about the city coming from the perspective of a 19 year old is that Tallahassee, Gainesville, and Orlando are all only 2 hour drives away.
Miami is a different ball game, though. Definitely the most liveliest I've been to although the cost of entry is bit high if you want to enjoy the funnest things in the city (like clubs, etc). South Beach is great and basically is what you see on TV when people talk about how great beaches are in Florida. You see a lot of beautiful women in the city and it's probably the most diverse city in the state. Lots of Latinos and Asians in comparison to the rest of the state. I'd say it's almost impossible to get by in the city without knowing at least rudimentary spanish and you won't live there without learning any. There are a lot of top universities in and around the city (Florida International, Florida Atlantic, University of Miami) so it's a very lively college town in addition to all the things mentioned above. On top of that, you have the world champs Miami Heat, along with the Dolphins and Marlins, along with the college sports, so it's very healthy in that department as well although Miami sports fans have gotten the reputation of being wishy washy. Anyway, Miami is definitely the funnest city in the state but also the hardest to live in. You have to be, if not street smart, just smart about yourself and focused on what you want to accomplish in the city because it's easy to get distracted and/or played with all the things, people, and temptations around you. Cost of living is also one of the highest in Florida. Wouldn't recommend living in Miami unless you're a college student, rapper, professional athlete, or well established business person/lawyer-type. Honestly, if you don't have a particular reason to live in Miami, then you really shouldn't.
Tallahassee is fundamentally a melting pot of the entire state. It consists basically of the state legislature and FSU/FAMU/TCC students and people related to them. If you grew up in places like Jacksonville, Pensacola, Tamp, Orlando, etc chances are you're going to see a lot of the same people when you go to college in Tallahassee. It's a very college type town although because of the geography of it (a bunch of hills basically) it doesn't have the same hustle and bustle as Miami per se'. That said, if you like the party life as a college student and don't mind seeing a lot of the people you came up with (if you had lived in Florida) Tallahassee is great. Also good if you're a PoliSci/Law student due to the state legislature being so close. Even better if you go to FSU. I'd also say, not being politically correct, that there's a distinct difference between the white-half of Tallahassee life and the black half. It's not self-segregated or anything like that, but there's just an intangible difference between what black people do and white people, speaking generally. It's inevitable when you have the number one HBCU along with FSU in the same town. Tallahassee doesn't have a beach btw.
Orlando, is...well Orlando. I haven't spent as much time there as I have the other three, or rather, I haven't seen as much of the city life as the others but I think Orlando is very much a sort of combination of the three if that makes sense. It combines a bit of all three of them, with the beaches and tourists of Miami since it has Disney World and Universal Studios Theme Park, a major university in the University of Central Florida, a semi-premiere basketball team in the Orlando Magic (although they're down and out right now), and the general business friendly/settled atmosphere as Jacksonville. If you're looking for a little bit of everything depending on where you're at in the city Orlando is probably the best place.
Only other town I've been to is Gainesville, which is basically University of Florida city aka Gatornation. I mean really...that's all it is. It's a place in the middle of nowhere dedicated to UF lol. It's one of the more boring towns with a premiere college that's the only place for any real fun or point of being in the town imo.
So there you have it. I hope I helped a little bit. I know the post is long but I wanted to give you a sense of the full Florida not just what people generally say. It's very diverse state with some unique sensibilities. I haven't even gotten into the political structure of it which is just as diverse as the state itself. Personally, after living here the past 19 years (my entire life) I'm ready to move on and experience other places. I suppose I could see why someone who has never been here before would be excited but I'm frankly tired with it and the people in the state for the most part. But I guess living in one place since child birth will do that to you.
