I've used RCCL's bus transportation twice before from Orlando to the ship-it's a normal "cruise" type bus-give the driver your bags and that's the last you handle them until they arrive in your cabin. Go down to baggage area, get your bags from the airline, and walk over to the bus area, where there are people from all the cruise lines to help you get on the correct bus. In my opinion, it's almost effortless-may be a little pricey for some (about $55 each) but worth the cost to me.
You're going to LOVE Mariner!!
Have a great trip!!
(I thought the food was great-make sure, if you like steak, you make reservations IMMEDIATELY upon boarding, at Chops Grill-Fantastic Food-costs $20 each extra, plus a tip if you wish)