I'm similarly sized to you in the waist/hips, and also 6'0", so I totally understand your pain!  Pants shopping is the WORST.  I have an old pair of Marmot hiking pants that are slighlty stretchy, and I've been wearing them for more than 5 years now to the point where they are almost threadbare in places, but I cannot buy that style anymore and I refuse to give them up!

I know that REI has Plus sizes, but the extra room afforded for the butt/thighs in Plus size pants doesn't usually translate for sizes 8-12, in my experience, even though many of us are at that in-between size.  I am quite fit and just happen to have very strong/thick thighs and butt.  Women's Carhartt pants are absolutely NOT made for anybody with a butt (and have zero stretch).  I work outside and need heavy work pants as well; I find that Duluth Trading Co has great sizing for me personally, and unfortunately have not found anything that fits quite as well at REI in the work pants department.  For ski pants, I tend to simply get at least one size bigger than usual- since I typically would wear a base layer anyway, it doesn't seem to really matter for looks.  When it comes to regular hiking pants I find that I usually end up trying on 10 pairs and *maybe* find one that I like.  At least these days I can find Tall sizes, which is a nice change from years past.