I like your idea of starting around Key Largo. Summer in the Keys is not prime season, so expect it to be hot and humid, and not a lot of breeze... unless a whirlygirl moves in. If you have air conditioning on your boat, it will go a long ways towards comfort aboard. I see you are from Houston, so I know you are familiar with the heat. :wink:
If you start at Key Largo and there is an issue with a tropical storm or hurricane ('tis the season), you avoid much of the evacuation traffic, working its way up the Keys. It is nice to go down one side, and come back the other. If weather becomes a concern, you can always get to the other side.
I am a fan of Bahia Honda State Park, south of Islamorada. They have a marina (more like a sea wall to tie to) that is very protected. And, a sandy beach (not a lot of those in the Keys). There are plenty of places to anchor in the Keys. The Waterway Guide to the Florida Keys is a good cruising guide to have - it shows places on the water as well as places on land (like grocery stores, laundromats, etc). Plan a few days in Key West so you can "waste away." The touristy stuff, like the Conch Train is a good way to get an overview of KW. Eat at some of the restaurants (on the shady side of the street) with outside seating to watch the "Duval Crawl."
If you decide to head to Ft. Jefferson (the Dry Tortugas), be sure you have water, fuel, and stores with you, since there are no shore facilities there, other than the Fort (which is a National Park). Great snorkeling there. If you don't want to do it with your own boat, you can do a daytrip by seaplane or the FastCat.
Enjoy the trip, and post some updates and photos.
Best wishes,
Jim B.