In my youth I worked at the model railway in Weston-super-Mare in the mid-late 1980's. This was in sea-front premises leased from the council. The owner (Brian Oliver) used to open at Easter, then close until Whit week after which he'd stay open until the end of the tourist season at the end of September.
He used to have to take work over the winter months, but he made a living out of it. I believe he was involved with a similar set up in Torbay somewhere back in the 1960's.
Although a tourist attraction, the theme was the history of railways, so you had Rocket and Locomotion on the top level, running down to modern image on the lower levels. I really wish I'd taken photos back then.
I remember the layout was based on a series of loops on different levels, each with multiple trains on each, something like 40-50ft long by about 15ft. In some cases up to a dozen running on loops, shuttles back and forth. Control was traditional with reed switches under the track and magnets on the rear coaches breaking loops into sections and triggering switching to adjacent sidings via old Post Office relays.
Brian sold locos from display stands but it wasn't really a shop as such.
It really was an ideal job really!