Howdy!
I lived in Fl for 14 years, and I gotta tell you guys that for heat, humidity and bugs, that place is hard to beat. I carried a Glock 17 (grip reduced to G-19 specs) or a 5" 1911 daily for 16 or so hours in a Max-Con V.
As has been previously stated, if you go with a shirt that does not form fit and has a little bit of blouse to it, preferably in a print or dark color, you should have no problem whatsoever in concealing it in a good IWB.
If your wardrobe requirements will not allow an un-tucked shirt (office casual dress, for example) I am really fond of a pocket holster/ankle rig combination.
An ankle rig provides you with a larger, more powerful weapon than what can generally be carried in a pocket, but is slow to access (except when seated). The pocket holster is super fast from a standing position, but renders the gun inaccessable when you are sitting. The two work together really, really well in that they compliment one another (ie each is readily accessable when the other is not) and you automatically have a back-up gun as well.
Lou Alessi makes GREAT ankle rigs, btw. I recommend them highly.