Many years ago airlines would add some festive cheer in the aircraft by putting up just a little decorative touch here and there in tune with the season, few airlines, if any do that now.
I once took a KLM flight in the 1980's from SIN to AMS on NYE and as we passed various cities below us the captain would come on and announce "Happy New Year! We're flying over XXX and it's midnight here!", and with that there would be a cheer form all the passengers and the FA's passed out more Champagne, by the time we reached our destination, quite a few passengers were buzzed, funniest and most fun flight ever. Sadly, in today's security paranoia environment and cost conscious days, these kind of things are legends of a bygone era.