Come check out this friendly B&B (not cheap!) with beach only 100yards from the your room.
Make sure to stay a couple of days, ask for a room with ocean view and enjoy the atmosphere. Relaxed, friendly, loud but unforgettable. Rooms are very very plain, bathroom modern, balcony overlooking the cute beach and sky at night is awesome. Take the free hotel shuttle boat (leaves every hour) to down town Positano, get a gelato, relax at the Caprici restaurant (gorgeous food), shop at the "Antique" & get a beach dress for 10 or 20$.
If you're half board: take your lunch at the hotel & do dinner in Positano. Taxi boats will take you back to the hotel for 10 euros each until 5am.
Bottom line: I'd go back anytime, off season.
