The biting insects are bloody awful in August. They will drive you below decks and you'd better have air conditioning. We didn't, and had to pace the dock.
If the wind co-operates, it is a very fast sail from Key West past Miami with a fast Gulf Stream (perhaps 3 kt) beneath you. We were blessed with a westerley wind that night.
The approach is very shallow and it takes some getting used to. Don't even think of going in there at night.... it's a cardinal rule anyway.