What color should my girlfriends dress be to match my white tux :)?
Her dress should match your vest and tie with the white tux. So it depends on what you wear. Anyway, a white tailcoat is overboard for graduation ceremonies. The only time to wear a tux is prom, when you’re performing in a symphony orchestra concert, and your wedding (oh, and possibly your daughter’s wedding). Unless you’re in upper society (in which case you would be much better versed in dress etiquite far beyond my expertise) those are really the only events which require a tux. Invest in a nice navy or charcoal gray suit instead. You’ll be able to use it in the future.