The terminals at Port Everglades are actually pretty nice. They are large and bright. Location depends on the schedule for the day, so it's hard to predict distance from garage. It can be a bit of a schlep. If possible I'd suggest you drop off your luggage and one person and then take the car to the garage. A lot depends on how many/how big ships are in that day. But you will be out of the sun and protected from weather. If you don't arrive too early there shouldn't be that long a wait for a ship the size of Mariner, I'd think. Enjoy your cruise.