I have a pair of RL Bierley boots (brown, "waxy" leather, side gores, rubber sole) that I wear with jeans a lot. There's also something to be said for old doc martens. Maybe Frye boots
would fit your specs. My gf has a pair, though she does not own a motorcycle. They look really good once they're broken in and a little busted. I think they have combination leather/rubber soles, but none of the heavy lugs I think you're trying to avoid. Of course, orbitingio has a good point that a thrift store is a great place to find boots, long as you're comfortable walking in a dead man's shoes.