Day 2 day I simply use my normal messenger bag (bought from the Gap last year). There's nothing more inconspicuous then a normal bag. It carries my camera, film, and a couple of lenses in the pockets...right now it has in it an R2a+28/1.9 on with a 50/1.5 Nokton and 21/4 Skopar in a side compartment.
If I need to carry more, then I have a Domke F2.
If I need to carry more, then I have a Domke F2.