Hotel Holiday in Cartagena also has a lot of information.
If you kind of have a date set in your mind, you will have to take anithing that comes or goes around that time.
We had some difficulty getting off the San Blas to Panam City.
We were dropped on El Porvenir.
The locals have to find the time in their "busy schedule" to take you to the city.
It is 1 hr by boat to the mainland then 4 to 5 hours by 4x4 to Panama City.
They were charging 5 USD per person for the boat and 25 USD for the jeep.
We got the ride for 20 each, but then the driver dropped us in the city, not at a guesthouse.
In Panama City, Lunas Castle in Casco Viego has good info on boats.
Get some cash USD in Cartagena before leaving, as the first ATM is in Panama City.
You'll probebly have to spend some time in San Blas before you can can go to Panama City.