Hi Paul, I was thinking of one of the Billinghams. I will only be carrying the camera and two lenses, but I usually want some extra space in the bag to carry things like - a water bottle, a lonely planet guide, and whatever souvenirs I pick up from my travels. Years of travelling and owning a few bags means that there are three things that matter most to me: (1) capacity, (2) weight, and (3) whether the damned thing has a comfortable shoulder strap or not.
I tend to favour messenger style bags. My current "camera" bag is a Crumpler - which strictly isn't a camera bag, but the camera went into it without any protection whatsoever.