I really can't discuss the overall structure as what I build is for our tropics, ie; rain. My roofs are sloped, but very little. Our issues are heat, and air circulation.
But when it comes to benches, I really have a good working system that should work in all climates. I use 4X4 PT posts and concrete them in the ground. I then frame them out with 2X4 PT boards and decking screws. Where I can't get behind to put a screw in, I use metal brackets. The most expensive part was the roll of hardware cloth that I had to order from California. 1# squares by 3' width, in a 100' roll, about $150 w/shipping to Florida.
Think of it, its 100 linear feet of 3' benches. I use stainless staples (size 50) to hold the cloth down...
This is what the benches look like...
A little closer...
(I know, just another opportunity to show of a C. Gigs var Sanderiana.. lol)