Knobby
I agree - go for it. I flew Naples - Key West last year, and then back from Key West to Merrit Island (near the Kennedy Space Centre) with Mrs PhilD in a 172 rented from NAC. These were two of the best flying days I have done. At the time I had about 150hrs TT.
On the way down to avoid a long overwater stretch we flew towards Miami, and then turned south to follow the road down the Keys. We had no lifejackets, but we were talking to Maimi Center, then Key West, so I never felt that we were significnatly exposed in the event of an engine failure.
Down the Keys you can just follow the road - I was asked to keep the land on my right on the way down. It was easy to navigate as all the islands make such good landmarks. As you get close to EYW you need to call the Naval Base just before the town and they could ask you to stay (say) 5nm away. After that it's simple to find the airfield.
On the way back on the advice of some people in the FBO at Key West we flew up the east coast past Miami, 500' altitude and 1/2 mile offshore, under the Class B. This is a great flight and gives you a fantastic view of Miami.
Have a great time - Key West is a great destination - only wish I was going too!