We haven't really "decorated" an offsite room (nor onsite, for that matter), but we HAVE done things to make an offsite stay more "Disney-like." These things have added to our enjoyment, especially when the kids were younger:
--- Disney music for the car rides to/from/between the parks
--- Mickey bars and other ice cream novelties for our timeshare
--- Mickey soaps & shampoos in the baths
--- put lots of Disney beanie babies around the room
--- made Mickey-head pancakes in the morning
--- new Disney swimsuits for the kids, which they found their first morning there
I think that bringing a string of lights and some pretty garland or bead strands to drape from a few inside fixtures or tape onto metal/vinyl porch railings would be really nice at Christmastime. We don't go all out to decorate our home at Christmas anyway (just a few light strings inside and out, some evergreen garlands and lots of candles). So this kind of thing would feel very festive to us if we were away at Christmas.
Whenever we go on our timeshare vacations, I ALWAYS bring scented votive candles in sturdy votive glasses. I stuff them into sneakers so they won't break in transit. The pretty scents set the mood for the time of year and remind us that we're on vacation. It's romantic too, since we often have a nice jacuzzi in the MBR.
I don't think you're a loon. You just want to make your vacation more special.
