I'm with Klav on this one. How to pick just one memory out of 40+ years of riding? It's impossible. The first time I ever got my knee down at Cadwell Park race circuit on my Triumph T595 was great as was the ride there and back.
Memories of touring down to Portugal through the Picos Mountains will be with me to my dying day as will rides in the Smoky Mountains, the Colorado Rockies and the Blue Ridge Parkway whilst on holiday in the States - that latter on a Honda CBR600 which was FUN! Actually, there's a theme here I've only just spotted. Mountains! Love the twisty roads you get in the mountains as well as the scenery. So, add to that list the Scottish Highlands, North Wales and the Alps! Been to all and loved them all.
Been scootering for only the last 8 years and my favourite memory (so far) from that genre was last year's ride up to East Yorkshire, again through the mountains of the British Pennines - the Peak District.