I've just bought some Red Route kevlar jeans from http://www.riderz.co.uk and i have to say, even with the armour in the knees (which is removable) they are the comfiest pair of jeans i own.
they have kevlar all over your ass, down your hips and on the knees and appear to be well made to boot.
plus i ordered the Red Route Rider jeans, and they sent me the Ultimate Rider ones, which are £10 more, so that was nice.
I've got some Draggin jeans which I think are much the same... never felt quite right wearing them though, feels strange without bulky material like my textiles!