When I went to college the layout came down. Moved out of state after college and the trains stayed home. Though I was buying and selling in the meantime to start checking off "must haves" for that "someday" layout. Moved home after a couple years and was allowed my old 4x8 table in the basement for about a year until my parents decided they wanted the basement back. Now everything's in a storage unit until next summer when my financial planning will come to fruition and I'll be shopping for what I have been referring to as a "train room with a house attached/over it".
A small loop (sometimes I can sneak two) does end up under the Christmas tree every year and last year I even had my (at the time) two year old niece working the controls pretty well. Looking forward to this year!