My three are:
Hepton Wharf - fell in love with it and used it as direct inspiration for the overall "feel" of my own layout
Wheal Elizabeth - shows just how much you can fit into a small space and still make it really interesting
and lastly, absolutely anything by Iain Rice, but then it may be him rather than the layout that is inspirational.
From the mists of time a bit - Heckmondwyke, and still around after all these years, Bodmin - because they were there and were the first layouts I can remember seeing in any detail