Honestly, setting up the monorail underneath the tree is the "event" I look forward to most over the holidays. Our set has grown over the years to include:
Monorails red and blue (the doors actually open)
Hotels: GF, Contemp, Poly (Including signage), Wilderness Lodge (which takes a long time to set up since it is the Lincoln Log set).
Magic Kingdom accessories: HM, Astro Orbiter, Space Mountain, Castle, Dumbo (Also two trees and a lightpost)
Epcot: Spaceship Earth & The M:S Rocket
MGM: The Hat along with the character accessories which I set up outside the hat.
Animal Kingdom: AK Tree along with accessories
TTC switching station
It takes up the entire living room and then some. I have two loops going, a MK/resort line and an Epcot line. I also set up MGM and AK to scale and in there appropriate directions. Also, I take all the prince/princesses and put them each on a hotel that would roughly correspond to there "background" (snow white/prince at WL, Beauty/Beast at GF, Aladdin/Jasmine at Poly, etc.). It takes a long time to complete every year but it is most certainly a labor of love!
~Amy