If we're talking about theme parks and lines, JT, I have to disagree about lines being shorter in the summer. Lines are longer b/c most of the tourist come from other states and actually ENJOY the heat (masochists), and that is the only time their kids are out of school. SWA is SLAMMED hard from about late April until early Sept. Best time in my opinion to visit Florida is probably mid-late Sept (maybe into early Oct) or Feb. Temperatures are not too bad, and the crowds are fairly low. If you're not doing the theme parks, then pretty much anytime is good. After working at Disney, Universal and Sea World, you can't get me in one of them during the summer.
As far as Sun N Fun, it's more humid than hot (but then again it's like in the 80s in Jan right now. grrrrr), but bring sunblock. The sun is killer. Although it was cool to watch the airshow sitting under the wing of a Spitfire.
