Dress code? Well, it's winter and it's Minnesota, which means your flannel pajama pants are not only practical but probably socially acceptible no matter where you Jingle your Jangle on a cold December night. As for me, I'll be wearing sequins and showing some cleavage. It's the holidays! So let's call the dress code "festive flirty," like this happy young woman with very natural hair color seems to be all about. If you're hopping, come as you are. Its YOU we want to see!
(Gents, tuxes would be definite overkill. And yet, you look so darned gorgeous in them, so who am I to stop you if the mood strikes?)