If it's a nice day, I always enjoy a train trip over the Forth Bridge - either to North Queensferry to go down to the water and see the bridges themselves, or up to somewhere like Aberdour for a walk along the coast (you can follow the train tracks to Burntisland).
I love North Berwick too - always reminds me of childhood holidays (especially trying to swim in the North Sea - and my wife wonders why I don't feel the cold...)