One of the advantages of digital is the much under-used/discussed film emulation packages that do a pretty accurate job of replicating the look of a myriad of films. The beauty of this is that you can change "the film" you used to take the shot after you shoot. Using such software regularly, you find you get into a "routine" of what film you select - after the fact, for certain subjects:
- Children: Kodak Portra VC or Ultracolor 100
- Young adult portrait: Portra NC
- Adult portrait - Tri-X black and white, low contrast setting
- Old people portrait: Tri-X (regular contrast)
- Dark non-rural setting: black and white - match film to ISO used to take shot (seems to matter more than "what film"...)
- Bright, outdoors, colorful: Slide film that matches ISO used w/ camera. Velvia 50, Kodachrome 25 sometimes.
- Indoor flash "grab shots" with people I often use Ektachrome 100 - the 70's emulation with a blue-ish tint. Reminds me of the way the snaps I used to see when I was a kid looked. Very 70's, but kinda cool retro look. I like it. Subtle but noticeable - if that makes sense.
General rule of thumb:
black and white people - Tri-X, low contrast
old peole - Tri-X regular contrast
black and white low light - TMAX - 3200
Outdoor, colorful - slide film with saturated color - Velvia, Kodachrome 25
Typical indoor group shot with a flash - Ektachrome 100