I think RCI's transfers depend on the number of people as far as cost and comparison to taxis, etc. I think in Florida, going to and from Port Everglades from FLL, their costs were pretty competitive compared to a taxi if it was just one person.
Also, ask2112, if you have any carry on luggage you want to bring on the cruise, keep that with you on the bus, and not underneath the bus in the luggage compartment.
2007 - Majesty of the Seas
2009 - Enchantment of the Seas
2010 - Freedom of the Seas