If you are going straight from BCV, you have several options:
BUSES or BUS+MONORAIL:
Take a bus to any park and transfer to a bus to Polynesian. Our personal preference would be a bus to Magic Kingdom because then you could hop on the resort monorail, and at the third stop you would pull up on the second floor of the Great Ceremonial House at Poly, which is where you will find 'Ohana. (We like pulling up to the Polynesian via monorail.)
MONORAILS ONLY: If you are able to walk through Epcot, go through the back entrance of Epcot in the World Showcase and walk through to the front of the park to exit. Then you can take a monorail from Epcot to the Transportation & Ticket Center. From there, you can either walk to the Polynesian or transfer to the resort monorail, where getting off at the first stop you, pulling up on the second floor of the Great Ceremonial House at Poly, which is where you will find 'Ohana.
BOAT+BUS:
Take the boat from Yacht & Beach Club to Hollywood Studios. (This may be a bit more leisurely.) At the Studios, transfer to a bus that will take you to the Polynesian. Once inside the Great Ceremonial House (main building at the Poly), take either the elevator or stairs inside to the second floor to find 'Ohana.
Have fun! 'Ohana is one of our favorites!
