Luckilly you can get to Key West from Just about anywhere.

You have a few options, most of them involve some sort of transfer in Southern "Mainland" Florida. Either Ft Lauderdale, Miami, Orlando, Tampa, Ft Myers etc. Rememebr that Key West is the southernmost city in the Continenrtal US, When you're in Key West you're actually closer to Cuba than Miam. Key West is only 90 miles from Cuba!