The thread title really caught my eye. I was reminded of the O gauge train set that my dad bought for us boys as a Christmas gift back in the early 50's. It was a diesel engine. Diesel engines were just getting popular back then.
In the 80's, my wife (knowing my love of trains) bought me a HO gauge set as somewhat of a joke gift for Christmas. Well, that joke gift turned into many, many hours and many, many dollars of work and delightful enjoyment.
I added steam locomotives (you will find that these can be very expensive, but wonderful works of art and nostalgia). I built the layout, buildings etc. and put as much realism as possible into it. Even down to the grout in the tiny bricks.
Everything has since been put into boxes, looking to be resurrected some day. Since we are guardians of a 8 and 1 year old boy, I am being moved by this thread to once again setup the trains.
I even had one nephew that asked if he could have my collection when I die. Personally, I hope he has to wait for a long time.
If space is a problem, N gauge is the way to go. Too small for some. HO has the most options.
Give a big TOOT, TOOT to Mo for me.