Plywood specs from the user point of view

I'm working in plywood mill in Brasil. We are planing to start manufacturing Marine Plywood. The british BS 1088 and APA standards are giving a lot of freedom in wood species choosing.
I would like to know, from the builder point of view, what are you looking for when you are buying marin plywood:
- flexibility?
- wood dencity?
- special wood specie?
- wood specie with higher decay resistence?
- higher fisical resistence (proporcional to wood dencity)?
- decorative apperance?
How much more will you pay for a better plywood (in percentage more than simple exterior plywood)?

I would like to thanks for colaboration for criating better product for the boat building market.
You can contact me directly to my work e-mail: amitk@brascompdobrasil.com.br

Amit Kenny