We've been twice - Spring, 2021, and April of this year.
As noted upthread, the prices in the winter are peak season, and Key West lodging is WDW expensive, so know that beforehand.
But, IMO, the drive along the islands is one of the better on the North American continent. Blue sea, palm trees, tropical islands, bridges. Take your time, and make frequent stops to see things up close. There will be considerable traffic. Some of the old historic bridges are still standing and worth looking at.
This place is notable for a stop, and is a pure tourist trap. However, it seems to have captured the Keys vibe quite effectively. They play Elvis music over the loudspeakers, and it works. Good food.
https://www.robbies.com/
At Key West, we found these places interesting.
https://www.hemingwayhome.com/
https://www.floridastateparks.org/parks-and-trails/fort-zachary-taylor-historic-state-park
https://www.trumanlittlewhitehouse.org/
https://www.melfisher.org/
https://www.kwahs.org/museums/custom-house/visit
We did a sunset sailboat cruise. Worth it, we thought
https://www.viator.com/Key-West-tours/Sunset-Cruises/d661-g3-c5638
Everyone, and we mean everyone, gets their picture taken here. Go early in the day, otherwise, long lines.
https://cityofkeywest-fl.gov/Facilities/Facility/Details/Southernmost-Point-44
Duvall Street is the Key West version of NOLA's Bourbon Street. Perhaps a little less coarse than the original.
https://www.tripadvisor.com/Attract...val_Street-Key_West_Florida_Keys_Florida.html
Note that roosters and chickens run wild throughout the lower keys. To me, it really adds to the local color. They call them "gypsy chickens."
https://www.floridarambler.com/florida-keys-getaways/key-west-chickens-key-west-roosters/
We've driven the Tamiami Trail twice, and you get a good view of part of the Everglades.
https://en.wikipedia.org/wiki/Tamiami_Trail
We spent the night here, just about the end of the road Eat stone crab claws. Airboat tours are available, but we didn't go.
https://www.tripadvisor.com/Attractions-g34210-Activities-Everglades_City_Florida.html