As you're shooting medium format, unless you want really big enlargements, I'd go with a faster film like Fujifilm 400H or Kodak Portra 400. The slower films are great, but unless you need the resolution, they can be a pain unless you've got a lot of light.

400H is a lovely film, Portra 400 gets more press on the various blogs, but I think 400H is lovely, muted, and in 6x6, more resolution than just about anyone needs.