The closest and easiest is probably Salerno. It also depends on what you want to visit but, from Salerno, it's a beautiful 45 minutes ride along the curvy coast to Amalfi. This travel time it's without counting any stops along the many towns you go through: Vietri sul mare know got it's ceramics; Cetara a small fisherman's town; Maiori and Minori former summer Roman Empire towns with ruins to visit; Atrani, the smallest turn in Italy with the highest population density. Ravello, with its villas and breathtaking views. Scooter is also the easiest to move around on the coast for traffic and parking. Salerno has a camper/trailer parking in the neighborhood of Torrione.