OK, I just did a quick walk around the office (trying not to look too weird...): seven women are in, three or four appeared to be wearing no make-up, the others had mainly foundation and perhaps a light blusher. Only one seemed to be wearing lipstick, and that was a subtle pink. No obvious trends by seniority, although the lipstick wearer was the smartest dressed and had had a major client meeting earlier on. So I'd say go with what you're most comfortable with.