Wow...we are just two days off the ship and miss it more each minute!
Hotel: we booked the Holiday Inn Doral (west airport) for less than $80 on priceline. This is probably too far for a family, but we got a rental at airport (thriftyjust off site) paid $40 and dropped off at Miami Beach.
All in all, $140 (Hotel, Car, Cab to port) this is a great way to pre-cruise. We stopped and got some last-minute essentials, went to the beach morning of departure, had breakfast and had a relaxing morning sight-seeing without ever waiting for a shuttle or dealing with spring-breakers.
Great storage, big balcony but open to sunset bar, noisy and vibrates (aft).