I would love to do the drive but we're already kind of shoehorning this trip in, and between the connections through Miami and the drive to and from Key West it looks like it would take up a good amount of that time, versus direct flights in between JFK and Key West, which are just over three hours each way. Also, Mrs. 8893 has vertigo and doesn't dig long bridges over water, so I don't think it would be nearly as enjoyable for her. Finally, with the rental car shortages right now, adding a car to this trip seems unnecessary otherwise when it appears that almost everything in Key West itself is walkable.
As an alternative, would it make sense to rent a car for a day trip drive while we are in Key West? Or do you think something like the Dry Tortugas trip you suggested would be a better use of our time?