Coming down from Vancouver, B.C.

San Jose, Costa Rica? I think it's about the same either way, about the same amount of time in a bus. But if you go to Panama City it's one less border crossing to deal with. Does one have better prices or schedules than the other?

Copa airline offer fly from Canada (Toronto and Montreal) to David with one stop in Panama City. In David from the airport, you take a taxi to the bus terminal then a bus to Puerto Armuelles there are bus coming and going all day until 10:00 PM. For about $70.00, some taxis will take you from David to Puerto Armuelles; the bus cost $4.00 it takes two hours with the bus. You can also take the bus from Panama City to David the night express cost $18.00 it takes six and half-hours, you arrive in David at the same terminal were you take the bus to Puerto Armuelles. There is no advantage to go in and out of Costa Rica.

Fly to Panama City catch a flight to David Rent a car and drive to destination.

there is also a new airport in panama that would shave off about 4 hours of your trip.  I believe sunwing flies direct from toronto.  i am not sure of the name of the airport, but it is right off the pan american highway, close to the decameron resort, by Anton, and santa clara beach.