You could also try a small messenger pack in addition to a backpack (or by itself). It would serve the same purpose at the fanny pack, but a strap would hang across your body instead of using a fanny pack belt. I'm sure the fanny pack would work fine, but some people might not call them "fashionable" in today's world
. Messenger bags are definitely in.
I have this Lowepro Apex 140 AW, which includes an "All Weather cover that can be pulled over the bag if it rains. It will easily hold my K-7 with attached prime and an additional prime (generally up to 135mm focal length & 58mm filter diameter lenses). I can even keep the DA* 16-50 (without hood) on the camera and it still fits in the bag ok, as long as the other lens in the bag is smallish. If you were to keep the camera outside of the bag, there are easily 2 full spots for lenses, but you could fit 3 small primes in there no problem if you stacked or re-arranged the dividers. It also has a belt-loop so that if you wanted to simply put your belt through it instead of using the shoulder strap you could, but i'm not sure if it would slump over or something. I haven't really tried that, but I have put a strap through the belt look and used it in addition to the shoulder strap to prevent rotation around my body when I bend over to the ground.
It's not perfect but has been a good bag to carry my equipment everywhere. I take my camera with me every day to work (unrelated profession) and it's a good smallish bag to carry whatever primes I want to play with that day if I get the chance during my lunch hour.
Lowepro - Apex 140 AW