"...there's just a huge advantage to beginning the trip in a more timely fashion - as far as the seasons go - if you really want to savor and explore the Waterway..."

I'll second that. Like Jon I have done the ICW and the coast many different ways primarily because I had to get someplace for work, but if you want to cruise and enjoy the trip it pays to travel about the same speed as the change of seasons. Doing that you can carry the nice part of fall all the way south to Florida and carry the nice part of spring all the way north when you return.