Island City is mainly an FBO, they might have 3 172SP or so.
But once again, that island is 5 sq mi, sightseeing flights are gonna take their toll on you.
Don't get me wrong, it's a fantastic place to fly in and out, views are staggering.But would not want to fly circles around it every day.
Think about:
How much XC are you going to get?
How much Night are you going to get?
How much IFR/actual time?
How many Instrument and Commercial students?
How many Multi?
I think instructing down there is mostly a part time gig for the guys that fly the banners and sea-planes.
And Key West is a very expensive place to live, rent is ridiculous.
Most people that work on Key West live in Marathon or one of the intermediate Islands. That will give you 45min/hour commute one way.
Do a search on airnav and give them a call.