I'm 29. Sorry, no pictures handy at the moment.
Recieved an HO set at age 3 and that turned into a 4'x8' layout in our basement. I recieved an early Lionel Postwar set from a distant cousin at around age 7 or 8 and from then on O gauge was the focus. Largest layout I had was an 8'x8' "L". Trains went away during college (but never out of mind). I moved out of state after college but kept buying and selling; my method was to buy Postwar lots, fix everything up, keep what I wanted and sell the rest. Moved back home after a couple years and had a 4x8 in the basement again for about a year. Due to space restrictions the trains went back in boxes, but I'd bring as much out as possible for Christmas.
I only run conventional as it's always been easy to work on; looking back, teaching myself to fix Postwar Lionels probably contributed to me going into engineering.
Currently my financial plan is to be house shopping next spring/summer (or should I say "train room shopping" with a house attached). Pretty much all the trains just went into a storage unit for now to free up some space.
I've never lost interest and never stopped planning for the next layout!