I've been trying to settle on one film for a while now and just can't do it.
I used to love the grittiness of black and white film and decided I should shoot it exclusively for a while and see where it takes me. That experiment didn't last very long. While I still love the grain and the whole experience of developing my own film, I soon grew tired of the monotone! I love Michael Kenna's work for example but it's a mystery to me how he can refraining from shooting color film ALWAYS.
Once summer came I felt I need to pop in some color film. I haven't shot a roll of black and white for 3 months now!
I really admire people who pick a film and stick with it. I can't do it. What works best for me is actually shooting one thing on one film.
For example, I used to bring different types of film with me when traveling and it turned out to be the same damn problem I had with lenses and cameras. I just hate having to choose which one to use. The less I bring the happier I am. Furthermore, it also makes my shots more consistent. At least on the level of albums.
For my California/Seattle trip in April for example I only brought Provia with me. The same thing for my summer vacation in Yamaguchi, Japan. I was away for 10 days and brought only provia film, but two cameras. My Leica and my Holga. Next challenge will be to restrict myself to only one camera at all times.
I can't see myself however going on a long trip and only bringing the Holga.