These should get you started. https://activecaptain.com/ http://cruisersnet.net/ http://www.waterwayguide.com/ http://lists.samurai.com/mailman/listinfo/great-loop http://www.coastalguide.com/IntraCoastalWaterway/ http://www.skipperbob.net/
Much better going up than returning to FL If you are experienced then go offshore in displacement and use the extra 6 knots you gain following the gulf stream. Probably average around or slightly over 1g/mile but going south figure 3g/mile.