Only hotels near the MIA airport (are you flying into MIA or FLL?) will offer airport shuttles. Those are a good option if you just want dinner and a bed, but you won't see much/anything of Miami. Hotels in the Blue Lagoon area near MIA are often suggested - Hampton Inn is a cross the street from a strip mall with dining, fast food plus grocery/liquor and drug stores for any cruise shopping you may need to do.
When do you cruise and what's your budget? Prices vary with the season - the $300+ room in Feb can go for $100 or less in August.