Follow up question from someone with a similar situation - how long is the bus drive?

We drove it in a car in 4 hours. I would expect the bus to be closer to 5 hours or 6 depending on the number of stops and fog or traffic on the road.

There seem to be several ways to do this. One is the bus, which goes to David first and then to Almirante, yes? Another is the shuttle run by Habla Ya, which goes once a day. It is much more expensive than the bus, but also much faster. Or at least this is what I have been able to learn. Florence probably knows better.

Jean is correct. There is a couple of shuttles that leave directly from Boquete. One of them is run by one of the local hostel in town as well as the one for Habla Ya. The last I saw the cost was around $60 a person one way. With the non-stop feature it's a nice way to go. A cheap car rental is $45 a day and then you have to lock up your car in Almirante which is another $5 a day. So it's the same cost. Take the shuttle! :)

Definitely take the public bus system to and fro from David to Boquete. It is simple and easy to do AND cheap.