If you're planning on actually doing anything in Miami the RC Palm Beach is out, that is too much driving to do every day. On top of that, it's not a very good hotel, and if you're in Palm Beach, The Breakers is the way to go.

The RC Key Biscayne is a nice hotel, but I haven't been there in years so I don't know if it's fallen off. Also be warned it's 20+ minutes to South Beach traffic depending.

Haven't stayed at RC FL.