If the wind is hard out of the east, Hawke Channel can be unpleasant and sheltered anchorages are not easy to come by until you get to Marathon. Also, be prepared to dodge crab traps all the way down.
This being said, I found the ICC, which follows the west side of the Keys to be a great alternate route. It gets less boat traffic than Hawke, offers many quiet spots to drop the hook, and is almost totally sheltered from an easterly wind.
From Miami its an easy cruise down Biscayne Bay, under the fixed bridge, through the Rte 1 drawbridge, and you're home free. Water depths were not a problem for me and I draw 4'6".
Have a great trip!