I fish Florida flats all the time. My standard leader setup is an 8' leader with 3.5' of 30# hard mono, 2.5' of 20# hard mono, 2' of 12# fluorocarbon. Of course this varies as I cut of flies, but I rarely let the leader get below 7'. I use a 1' bite tippet of 20# fluorocarbon when I'm after toothy critters, but for redfish and trout I rarely use a bite tippet.

When I'm fishing a sink tip line, I use a straight 6' 25# fluorocarbon leader with 1' 12# tippet.