Wood for boat benches

[easyrider25]

ripped out some old boards that were well past their prime on my boat.  Any recomendations on what to replace them with?  They looked to be treated plywood but wondering if getting something different would work better.  Such as a piece of 1 x 12 pine and throwing a few coats of polyurethane on it as well?  The boards I am talking about are for the benches.  

Also, replacing the seats in there as well.  Previous i had the the vinyl foam seats.  When shopping around i am seeing a lot of the molded plastics chairs.  Any preference out there for durability?  Vinyl rips but wondering if the molded crack or break?

 

Thanks for any feed back!

[BringAnExtension]

I am in the middle of a rebuild as well.  The carpet needed to be replaced, and the best way to do that was to remove things, which turned out to have some rotting boards, which led to more removal and this is how it currently looks:

 

Most of the wood in my boat merely need a new coat of paint.  However, you can see the framing in the bottom picture are all rotted.  I have actually been thinking of replacing it with some 2x2 cedar.  Hoping that will be better at avoiding rot.  I also need to replace the deck above that frame, it had gotten a little soft and I am going to lay a new piece of treated plywood on top. 

Probably the best for replacement would be marine grade plywood, but it is expensive and not convenient for picking up over the weekend. 

Of course, I have never done this before so I am not speaking from experience.

[Billy G]

How'd the project turn out?

[BringAnExtension]

For mine, I just started putting things back together yesterday.  I will provide updates as I make progress.