Great posts, one and all. Here's my $0.02 about appearance. I have a few brass whistles and some nickel and one sterling instrument. I have found that Pro Mark cymbal polish works well on ALL of the metals. The smell is a bit strong when you put it on, but that subsides. I have been asked by people (INTELLIGENT people) how I was able to get a set of GOLD whistles. And, the shine lasts about 3-4 weeks. I buy the stuff in pairs since I swear by it.
Good luck and happy whistling.