I am also a fan of Duluth Trading and I have several of their pants. Some of their items will work for office casual, although most are definitely for work. My favorite dig pants are made of their Fire Hose material and work great.

I also like 5.11. Some of their cargo models would work for office casual.

Pockets are fairly easily to modify and reinforce.Fabric stores will have premade pockets, ideal for replacement.