If you need to get to or from the MCO airport and go to a hotel or seaport in Miami, you might consider using a shuttle instead of a bus.
Buses take upwards of 8 hours to get from Miami to Orlando whereas a shuttle takes just over 3.5 hours. Private shuttles are good for people in groups. Groups can rent out a whole shuttle and leave it up to the company to sort out the traveling mess.
Shared shuttles are good for people traveling by themselves and don't mind sharing the van or car with other people who are also traveling alone. Check out this place if you need a reliable company for Miami to Orlando bus tickets.
