I assume you mean the ICW from Norfolk to Miami annd not the W. Coast of FL or Gulf coast which are quite a bit more shoal and have lower bridges.
From Norfolk to Miami you will have NO problems with bridges except for the Julia Tuttle bridge in Miami...You can avoid this by going outside from Ft. Lauderdale to Miami which is a daytime trip in good weather and is a heck of a lot more pleasant than negotiating the 17 opening bridges between the two cities.
Depths will be much more of an issue for you as shoaling in numerous spots and lack of dredging has increased. We too have a 6ft. draft and very recently came north on the ICW without bumping BUT...
- We did a LOT of pre-planning and knew the trouble spots before trying them. Skipper Bob's guide and website is a must have and Tom & Mel Neals bi-weekly updates on the BoatUS.com Forum under East Coast Alerts are critical. We marked up our charts accordingly and planned our daily trips to take advantage of tides where needed. Since GA and SC have 8ft tides...you can get through anywhere if you can wait.
- We DID go offshore between Georgetown SC and Beaufort NC as we judged the shoals and lack of enough tidal help too difficult in Southern NC at Lockwoods Folly and Little River Inlet. Trip was an easy "overnighter" in settled weather. This may not be an issue by the time you go as dredging is planned for both these areas.
- You also need to get the hang of buoy to buoy motoring on the ICW, making rounded turns and staying in the channel despite wind/current and distances between markers. We've seen numerous boats with shallow drafts aground in places where plenty of water was just a few yards away. Looks easy but motoring for 10 hours a day...a few moments of inattention can result in a grounding.
Hope this helps...Have a great trip and try to allow time for exploration as there are lots of great little and big towns along the way!