Do you celebrate or feature holidays on your layout?

  everyday is like a holiday for me working on the layout and running trains

I have a box of small accessories usually picked up at  dollar store that I like to swap out and challenge visitors to find: various harvest-y items like pumpkins, hay bales and corn shocks, American and British flags, Christmas trees, Santa, and some seasonal items to carry on a flat or in a 'troublesome truck'. I used to be a bit more elaborate and change the farmed fields -- I have flats based on vinyl tiles that show furrowed soil, growing plants, and fallow fields.

I don't.  Layout will always be in late spring/early summer.  The wife decorate the house for each holiday enough that my layout is my escape from it.

I don't do anything special for my small O and S year-'round layouts, but I put up two O Christmas layouts. One is "fantasy", the other more "high rail".

Upper level is all Christmas, all the time. I don't really decorate the house for other holidays, though my wife puts out a couple of things for Halloween.