I have a couple of Billingham bags that I find very nice for day rambling with a small selection of lenses and one camera body.
But the bag I think more fits your request is a LowePro Street and Field bag. The whole lower compartment is for camera gear with dividers etc. The top is an open area for other kit....lunch, jacket etc fits quite well. This bag is not large enough for anything but a day walk though.
Not the greatest view of it...
I have many Lowe camera bags and all of them are first rate. I recently bought a Mountainsmith camera bag that is my current one, but it does not have any spare room for much other than a jacket a couple of water bottles and maybe a lunch, as I carry a pretty wide selection of camera gear.