Alum. wheel cleaner?

[Kudzupatch]

I have tried 2 or 3 commercial wheel cleaners and they clean the brake dust, don't bother the paint but they seem to etch the machined aluminum, leaving it looking bad. I have spend a good bit of time polishing to get them looking good again and this is just a pet peeve of mine.

So, what do you recommend to clean them with?

And, should I look at clear coating them next time I clean them? If so any recommendations as what to spray them with?