Oddly enough, a local city park in Virginia Beach, where I grew up, has displayed a menorah every Hanukkah since 1981, but Christian symbols there have been erratic (at various times there have been a nativity scene and a Christmas tree, but no one has bothered to do it regularly). It appears that the menorah is provided by a Jewish group that says it's "publicizing the Chanukah miracle." Someone this year asked about it, and the city told him he could put up a display, with the caveat that if he used lights, he had to provide an electric generator and $500,000 worth of liability insurance (this is probably why the Jewish group is the only one to have bothered). He did so, and now there's a Christmas tree up there, too.
This is interesting to me because the menorah has been there for years and years, and no one's argued about it. (In Googling, I did find one editorial about it, mostly complaining that if we evil atheists argue about nativity scenes, we should argue about this, too-- a point I find hard to dispute, even though I disliked the editorial in general.) It's prominent, too, being displayed along the major interstate that runs to the Virginia Beach waterfront. One of the articles adds, "Those interested in displaying a symbol - a menorah, Christmas tree or manger scene, for example - must apply with the city's Parks and Recreation Department, which takes requests on a first-come basis." It appears that the city has no awareness that religious symbols in a public park may be a problem. After all, it's a tradition.