Man, model trains - I used to be lucky enough to have an 8' X 4' HO train set in my room when I was young (up to about 16), and set up a 8' x 8' set at my house before I had kids. It had been in storage for years, and I just recently got rid of it all. The closest my kids had was Thomas the tank engine set and they outgrew it by about 8 years old.
I also used to do a fair amount of models (Testor's & Revell, mostly planes) and that got me roped into the likes of GW's 40K. A couple years ago I found myself marveling that I'd spend a week putting together a 40K tank for a game I'd never play starting the day I got it and had two model airplanes still sitting in their boxes from ten years ago. My kids? If it wasn't Legos and didn't come prepainted & mostly assembled, they wouldn't bother touching it.
Can I go back to the 80's now? My toys are gathering as much dust as I am - I finally have the money to buy all the toys I could ever want and too damn tired from work to play with them.