Sevenoaks to Tonbridge. Nothing special in terms of scenery etc, it is just where I commuted to school for 5 years on slam doors in the 80s. Many memories - the girls from Tonbridge Girls Grammar School, the lights going off in Sevenoaks tunnel on the compartment stock due to the tw*ts with chewing gum and 1p coins, the lights off AND the girls from TGGS!, the view of the flooding upstream from Tonbridge on the Medway during winter, the guards/parcels compartments that were my home on Wednesdays when I took my bike in for PE, the long wait on Sevenoaks platform for a train in snow knowing that if it gets to 30 minutes you are allowed to go home and skip school (why did it always arrive at 29.5 minutes?)...
Arun Valley - The lowest workload part of my route knowledge. And the scenary and wildlife you get to see while running on greens on the front part of a Horsham splitter.
Three Bridges to London Vic - I don't sign it, but during the practical handling part of my training I drove it often. London suburbia at 90mph, miles and miles of coasting, then the feeling of having done something worthwhile when you step off at Vic and change ends dodging the hundreds of punters.