I mostly rely on 4 bags for various purposes.
I have a Lowepro Fastpack 350 and as suggested before, is a nice spacious bag, the bottom half is compartimented and dedicated to photography, the top half is just an empty space which is versatile. Despite that, I find that the versatile space is generally not enough for travel and the space for hear is not well used unless you carry a fair amount of it. To me it works fine when I carry Camera + 2-3 lenses + maybe a flash, otherwise you risk carrying a bulky bag that is mostly empty.
I have a Targus Campus which is not a camera bag, is a laptop bag, but is very spacious and being a laptop bag is fairly padded and protects your gear if you are not carrying multiple items that will knock on each other.
I find the Think Tank Retrospective 20 really useful for urban use. It's more spacious than it looks, you can carry a fair amount of gear (more than you can carry comfortable on one shoulder) and the compartments are very adaptable so it's quite suited to mixed use. Also, the padding is not as thick as other bags so it may not be the best choice if you expect it could be hit but on the other side it has pretty good internal size for it's external dimensions. It is a bit pricey, but well worth it.
Finally the Lowe Alpine Travel Trekker II 70 which also isn't a camera bag, but a travel one. Also a bit pricey but it's incredibly versatile and has a kangaroo pocket for you to carry your day pack. So whatever bag you have to carry your gear, can be adapted into the backpack and carry it as a single item.
Considering you only intend to carry one camera with the attached lens. And I'm assuming this lens is small/medium, you may be better off buying a camera holster and use a travel bag instead of a camera bag.
Also mind that ideally you want to avoid carrying camera and clothes mixed up because of the humidity on the clothes. Specially used ones.
If I were to travel with only camera + attached lens with the bags I have. I'd carry the Travel Trekker and the Targus (as a daypack) attached to the Kangaroo pocket. I'd just make sure there isn't anything on the targus that can damage the camera.