REI sahara pants, how does the waist fit?

I think the pants run "just about right" — probably because of the elastic around the waist. Given that you are right at borderline, you should either try them out at the store, or order both sizes if buying online. Delivery to your local store is free, so no pain at all. For me, even when I have to pay for shipping, I would do it to help ensure getting the right size.

I'm a 34" waist and own the large. I'm sure they'd fit a 33" just fine.

OK thanks, I went with the Large, on sale for $17 and will shorten the length of the pants. They had the Medium in my size, but I think it sold out anyway!

So, this will be my first MYO (sorta) project.

Get one size larger. Thay tend to shrink a bit after several trips thru the drier. I'm a 33-34 waist too.
I own one size larger now and am happy. My old ones did shrink.

Eric
P.S. If you want a heavier nylon pair of pants W/O the zip-off leg get the "5.11" (that's the company name) Tactical pants. BEST I've ever worn. (5.11.com)