For your Florida trip check this link for some ideas-
http://www.lighthousekeepers.com/forums/Forum15/HTML/000006.html Depending on how "fast" you tour, probably could do the lights north of the Cape one day, south another. All are wonderful to visit. The two I would not miss are St. Augustine and Ponce Inlet. Both are wonderfully restored and have museums. Jupiter Inlet, Hillsboro Inlet and Cape Florida are also very beautiful and enjoyable. Hilsboro was a bit of a challenge to find.
For the northern Ohio coast--
We leave about 50 miles north of Indianapolis. Last Easter (98) we went from Marblehead to Erie, PA and home (from Thursday evening to Sunday afternoon). There are several that we saw but were not able to enjoy museum since we were there ahead of season. I would think you could pretty easily do the OH lights in a weekend. Be sure to get a copy of Penrose's book "A Traveler's Guide to Eastern Great Lakes Lighthouses" for about $15 - its' a good investment.
We just got back from a trip up along Lake Huron East shore (Canada) and some of Michigan's thumb. I would think you could also do a weekend trip (maybe a long weekend) to parts of Michigan without too much trouble. You might also be able to head over further along the south shore of Lake Erie and get as far as some of the NY lights??
Have fun, share your trip with everyone
Dave