An anti-static spray polish (Halfords (UK) and any good car shop stock them) and a microfibre cloth, should give at least a week before it starts to stick again, takes seconds.
I also keep a microfibre cloth in the car. For the dash, I wet it ever so slightly and it seems to work well. I also find it takes the fingerprints off the piano black fairly well.
Yep, microfiber cloth - the ultimate cure for safely cleaning dang near anything. Can't argue with success - and I agree - nothing works better on the piano black