What's the best material for a deck?

[71kidcasper]

I'm ready to install the new deck in my 20sf and I'm planning on doing it with 5/8" marine plywood. Is this a goood choice for thickness? I have already raised the stringers 3/4" and I'm planning on putting 1x3 mahogany on the bottom of the plywood and running it laterally, that way I will gain a total of 1 1/2" in height over the old deck. Hopefully this will allow for better drainage.