Christmas and put up a tree in the foyer if we have something there also commemorating Kwanzaa, Hanukkah, and Ramadan, the latter two not always falling at the same time as Christmas. It's unfortunate a Festivus pole was never a requirement. That none of these have anything to do with Christmas beyond a semblance of timing (some years closer than others) isn't necessarily a problem, except we typically don't celebrate anything else from any other culture at any other time. It's a grab bag of festivities that we use to permit a Christian celebration in a pubic school.
But this is an argument that suggests either we celebrate everything or nothing demanding a show of equality through equal time given. My counterargument is that this celebration is a part of the dominant culture and, more importantly, that it's a tradition worth fostering.