Actually out of Key Biscayne. My buddy came out of Haulover.
It's a freaking amazing ride down. Cross Biscayne Bay, through mangroves... and soon enough you are in The Keys.
Let me know if you ever head this way to make the run.
There is a little place called Coconut Palm Inn which our friends have been going to for years. Amazing small no frills place with an excellent location and non resort feel to it. Plenty of dock space too. BBQ's, hammocks...
I'm dying to make the Key West to Marquesas cross, but may have to trailer to Key West as it's a trek to get there on boat to then keep going:
http://www.fishingkeywest.com/marquesas_keys.htm