If you don't already know it, let me be the first to tell you, the Big Bend region of the Western Florida coastline (north of Anclote Key to Carrabelle and Dog Island) is not served by any sort of intracoastal waterway. So, you must choose to either cut the corner, or, staying WELL offshore, follow the Big Bend coastline around. If you choose this latter course of action, Capatin Doug's plan below has REAL merit!

Steinhatchee isn't much, but it's a good place to go to get across the gulf 70NM or so.  Then a nice cruise day is to go from Steinhatchee to Yankeetown.  Yankeetown is a teeny sleepy town, very non-touristy and not much to see, but the 10 mile trip up the river to Yankeetown is really very interesting.  The river is 10 to 20 ft deep all the way, with interesting narrow bends and changes in scenery from salt marshes and palm trees at the gulf followed by hardwood forests overhanging the river at every turn.  Then you go to Crystal River the next day. It's only 10 NM or so and you get there for lunch, swim and watch manatees that afternoon and you're ready to go to Tarpon Springs the next morning.
Doug