Bought the lined pants like these (but with the double knee) for my son last summer for fall. He has since outgrown them and I bought another pair plus a pair of the fleece lined jeans.
They are very durable, and comfortable, he loves them, he calls them his barn pants and work pants. They are true to size.
The flannel lining is just enough to add a little extra warmth in the fall to keep the chill off. They are very soft inside as well which is another winner with my son. I make sure he always has a pair of these with the double knee that fit.