I'm careful to only put displays up that mention "Winter Break" or "the Holidays," so I don't make anyone feel excluded regarding whatever their religious or non-religious deal is.  But I know that personally I'm not religious, and Santa and his reindeer were NOT present at the supposed birth of Baby Jesus, so I think it's okay to have those elements on display.  Anyway, here's what I put up this month:
The big central bulletin board, with Krampus and Narnia
          The Krampus is a real German Christmas legend/tradition that I incorporate every year because it's so freaky and fun.
I drew this Krampus depiction a few years ago, to terrify all the little children
It was way too fun for me to draw this frightened, crying little elf
The glass display cabinet with our tree and our Secret Santa gifts packed inside
          The last couple years we've started this cool tradition with the class that meets in the library 4 days a week.  (It's kind of like a homeroom class)  We do a Secret Santa gift exchange, and as soon as the kids start bringing their gifts in, we put them under the tree in the locking cabinet.  So the cabinet starts out kind of empty-looking, but fills up by the last day before Winter Break, when we have our gift exchange.
Well, they DO
Every library should have a glowing deer to preside over the graphic novels & comics
It's a little lackluster in execution, but I like the idea
I'm big on promoting the idea of "leisure reading"
Christmas lights strung behind the circ desk
This is my end-of-the-day, running low on holiday steam, WTF decoration.  Are they candy canes?  I think so.
          And of course I had to decorate myself a little, since I was wearing a green tie and needed something red.  Plus I just like any excuse to use my old-school Dymo label maker with interchangeable colors.