I enjoyed my two trips to the Keys. I haven't been to the Dry Tortugas, but spent one trip in a fancy condo about 2/3rds of the way down, and the other at an AirBnB in Key Largo.
There are a couple of things to note. I have been to tropical and subtropical locations in a lot of far flung places. The Keys fall into the category of not 'fancy' but rather beat-up and ramshackle in terms of 'vibe'. Also, there are only a couple of decent beaches in the entire chain. Most of the beaches are sort of silt/mud, not the nice sand found on the mainland coasts. So if beaching it is your thing, be warned.
We did a lot of boating (kayak, snorkel trips...which your timing is better for potential jellyfish swarms that can make summer snorkeling a misery), fishing, and wildlife/plant watching. On the Key Largo trip we did 1 beach trip, but that required driving all the way to Miami, and traffic is appalling, so be warned. The historical part of Key West was fun and interesting, otherwise it was too built up and touristy for my liking.
The Everglades are phenomenal for birding in the winter. But then, birding is one of my favorite activities in life. We spent a lot of time there on my winter trip to Key Largo.