Kristen, welcome neighbor...
Key Largo is *great* place to get certified. Do you already have a dive op scoped? There are a number of them that will go out of their way to make sure the site matches your experience level.
The Benwood, Molasses Reef, French Reef, Christ of the Abyss, Elbow Reef, City of Washington (wreck), Grecian Rocks, Hens and Chickens, Pickles Reef, are all good 1st dive sites.
I'd stay away from some of the deeper wrecks (Spiegel, Duane, Bibb) until you've got a couple (dozen) dives behind you.
The viz is usually very good, the reefs are in great shape, and the life is incredibly varied... from nurse and reef sharks to rays, turtles, morays, octopus (night dives), parrots, blennies, grunts, giant grouper, cuda, and the occasional megalodon...
The Keys can get a little choppy... so, if you're prone to feeding the fish from the gunwale, bring along a little Triptone or ginger snaps...
You'll love it! Dive safe... (and post a report when you get back).