Obviously there's nothing like just letting a train run, so my dream layout might be a small country station with a local industry to explain increased goods traffic and a really long scenic run in.
As a spectator I love some good shunting too (done well), though I can see the appeal of long scenic loops allowing you to run some long trains and let them snake through scenery, but on anything but a huge set up a loop still looks like a loop.
What I got very board of very quickly at exhibitions is what I call "How slow will your diesel Go?" layouts. Usually some form of fueling station, or marshaling arrangement, with umpteen diesel locos with sound, only one of them moving, just, a bit, if at all, and (sorry) palpable air of smugness emanating from behind the scenic backboard.
What I've found I do like at exhibitions is these same layouts when the owner nips for a drink or comfort break and the son or grandson is left in charge, because then lots of stuff starts happening and things start to move about the place.
