Have never been to the isles of scilly but have been several times to Jersey & i love it there as their is loads to do & see. For me Scilly would be too quiet i feel but if all you want is a relaxing time just lying on beaches etc go for it. If you prefer activities i would say go to Jersey.
Florida is quite a large place. Depends where you will be situated. I have stayed in Miami, Orlando & Clearwater which are all miles away from each other. The best beaches in my opinion are on the gulf coast ( Clearwater & St Petersburg area ).
Miami & Fort Lauderdale have great beaches too on the East coast.
Orlando is probably the entertainment capital of the world, although for many of it's attractions are better suited for families. ( Are you taking any children ? ).
There are many tourist information centres in Florida where you can pick up brochures & guides with money off coupons etc for attractions & stuff.
RE: Travel to Turkey....
Because i like seeing different countries & have been to 32 European countries but not yet Macedonia & Wizzair fly direct from London - SkopjeNot really bothered about the weather. Just like different cultures although didn't like Sarajevo much last year.