If not just going for a walk or to the shops, at least 2 bodies
For concerts: K-500 with 50mm f1/.7 (or 28/135mm f2.8) and K1000/MX or Fujica STX-1 with 50mm loaded with Tri-X. Nikon D60 with it's lenses as back-up in my backpack or when I'm taking photo's with flash & second-curtain sync lying on the side of the stage or on my shoulder. K-500 on my right shoulder/hip (free to use), strap of the analog cam going from my right shoulder to my left hip and attached to my pants and strap of the K500 with carabiners. Nikon D60 when carrying it, strap from my left shoulder to my back and attached by a carabiner. Instead of attatching the straps to the carabiner, I attach them to a key ring so they don't move around too much.
For weddings/events: K-500 with 50mm or 135mm, Nikon D60 with 35 or 50mm. One on the right side, the other on the left side.
City-trips/hiking/festivals: K-500's strap attached at shoulder height to my backpack's shoulder strap with 2 carabiners, in my hand or in a camera case on the side of the backpack. When not raining, often a lens in a mesh pocket of my backpack. Same setup for the analog cam I'm carrying at that moment at the other side. Other analog camera with different shutter speed and extra lenses in the backpack with the rest of my stuff.
Some events: Same as for city-trips but with a second analog camera with different focal length or film speed attached to backpack, same side as the other analog camera but attached high on the shoulder strap (shoulder height).
And I don't use a photo-backpack as I find a normal hiking backpack more useful (easier to attach stuff, size it down when not full,...)