Stay in Miami or road trip?

[snabzter]

I am thinking of going on holiday to Miami in April next year for 2 weeks. We will be flying in and out of Miami (decent flight prices for us). Any suggestions on whether it's better to stay in Miami for the full 2 weeks, although we will hire a car and drive to places, or is it a better idea to go for a road trip and stay in different places for a couple of nights at a time?

We would at least spend 3 or 4 nights in Miami at the beach etc. if we were to stay elsewhere during our trip.