Crosses and angels are examples of the first, trees and plants are examples of the second. I explain that a Christian symbol makes me feel excluded and that I'm sure they don't intend it that way. I explain that adding a Jewish symbol makes me feel included. Again, no one has ever failed to understand my point, nor have I ever been turned down. I am often asked about the symbol and that gives me a chance to explain how Hanukah is not the Jewish Christmas, but is a seasonal holiday in its own right.
Most people glaze over, but a few are interested and learn something.
I think this would be more offensive to the Christians, personally. But, yes, I don't like it much, either. Perhaps because I make no attempt to hide my religon, whatsoever. I don't wear a Kippa, but I refuse to work on Saturdays, and I take vacations on all the Jewish holidays. Others seem to respect this sort of behavior.