I've got a pair of teak directors chairs that are holding up well after 3 years. The canvas lasted about 2 years.
The amazing piece is a "dumpster find" folding porch rocker in some unknown wood. It had a chipping coat of bright red paint on it when I got it. It was repainted with Rustoleum bright red over a year ago. It still looks like new.
If you don't like plastic, maybe paint is the answer. Clear finishes just fail too quickly. I couldn't keep urethane on my porch swing in Memphis, so I know it's not going to work here.