A preserved layout done well can be popular - Dduallt and Goathland spring to mind. However there is too much tendancy for the anything goes on many which whilst acceptable as a one off can stretch credibility too far. I am working on a layout that can run as late 50s, mid 60s, late 80s and late 00s - the latter two being as a preserved line (the two periods due to trying run the correct locos at that date in contrast to anying goes). This will have a changeable scene across the front of the layout, a BR lorry depot with a small car dealers changing into it being entirely a car dealers and then it has been landscaped as a park with benches in which a vehicle rally is taking place.