I'm pretty tall and usually wear a 36" inseam ----- I wear a 34" Duluth inseam though. And they haven't gotten any shorter via washing.
My trick is to only dry them for about 5 or 10 minutes and then pull them out and hang them.
Try looking in on their site from time to time and 34s might be back. They make them in batches and some sizes sell out until the next batch. Sometimes they update and improve the design for the next batch too.
I wear their "dry on the fly" pants here in the lab. Very light and comfy.
I bit the bullet and bought a Gen 1 set of these (with the Alpha jacket too). They are more or less Goretex 3, tough as heck, and very easy to put on without taking off your boots. I think some of other Leaf models will accomodate knee pads that fit into a pocket (which would be very useful at backpacking camp if you are old like me). I bought them big enough to slip on over other pants for evening, putting on tire chains, building a fire. They are most certainly wind and water proof and warm enough for physical activity with a very light set of wool leggings under them.
About this time a year, dealers start clearing out their stock and you can usually find a pair for ~$350.00 if you look. Arcteryx Leaf is seriously expensive, but the Leaf line is still handmade in Canada (last I heard about 2 years ago) and they really do have a lifetime warranty. It's a "buy it once and be done" kinda thing. Please don't flame me yall. I know I'm a fool for paying that much but they are always in my gear and make me giggle when I actually have a reason to use them.
That being said, I consider them to be another layer and wouldn't wear them all day long unless it was really miserable outside.
I have a pair of Timberlines for hunting. They are pretty warm for summer wear so not all rounders, but meet your request for warmth and the reinforcement on the seat and knees is Gore-Tex lined which is a pretty slick feature. I'm a Railriders fan as well, and those Bushwacker Weatherpants seem like a good way to go, they are now on my list. If you're really going to be on your knees a lot, knee pads (either tactical or construction depending on your aesthetics) seem like a good way to go. I can't imagine wearing true briar pants made of canvas unless walking through heavy cover (upland game hunting). Most I've had are very stiff and not particularly comfortable when seated with knees bent.