not sure about the street skating, but the snorkeling is great. you can find charters all over the place with knowledgeable captains who can show you whats up. there are even catamarans that will take you out to the reef, and feed you booze all the way home. the night life is legendary. have a great time doing the Duval Crawl!
Looe Key is the best. Pennekamp is good too. The guys who run trips to Looe Key out of Ramrod Key are great guys and will only take you out if it's gonna be good. If there's been a lot of wind, the water will be murky and choppy, and they won't run trips anyway and rip you off, like some other shops will. I'd say Looe Key is the best reef diving in the US. There are also a lot of patch reefs scattered around the Keys that are little gems, if you know where to find them. Many are only a SUP paddle away. If you go during the open season, you can also get a license and catch lobster and stone crab. And if you get skunked, go to the supermarket and pick up a couple pounds of Key West Pinks.