Everyday, I carry in my office bag:

-personal stuff (mobile, wallet, keys,)
-Ricoh GRDIII (quick shots of products, macro, grab shots on the way)
-Nikon D3 or Leica M6 with 2 rolls, when the evening is not set

For casual walks around the city I carry in an old washed out cotton satchel:

-Nikon D3 or Leica M6 (very rarely with max one more lens)

For going out not specifically for taking photographs:

-Ricoh GRDIII with one spare battery - no bag needed