I wear 32 x 32 pants normally and ordered a Medium. There is enough room, I slide these on over my jeans and wear them to/from work. They have stood up well.
My only complaint is the knee armor isn't tight to you and sort of floats. I found a solution though: If I zip the pants into my Sidi boots, the knee armor will hold in place well, and it stops my jean bottoms from getting wet in the rain, so it is a double win.