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.

If you got kids, this is the place. If you like Fellini, this is it. Rooms are 240 w/ half board (lunch or dinner) w/sea view (August). Don't expect too much luxury, the rooms are plain but clean, bathroom modern. View: heaven. Where do you find your own little bay, little hotel w/beach front for that money in August in Europe? In Positano @ Le Sirene!
Until 10am you're ok - just before the crowds come walking down from the hill and head towards the 3 sqm public beach. Within 30min, the whole place looks like a favela. Other crowds "float" in by boat and head to the restaurant and beach "Da Adolfo", next door. It gets really crowded and loud. Until 5pm. Don't even try to do a siesta - forget it.
After 5pm, you're in paradise again. Dinner, evening, night is amazing. Family and staff are the kindest persons on earth. Eccentric? Probably. Foods great, breakfast just a bit too unpretentious.
Nevertheless, the place's a gem, unique. Come and stay 2-3 nights, it's worth the experience! Take the boat in Positano, 5 minutes later you're in a different world. Check it out.

We spent four nights here. The boat collected us from Positano 10 minutes after we called the hotel and we were warmly greeted by Sonia, the owner. Our room was basic, but clean, and looked out over the small pebbly beach. The staff were all really helpful and professional and the atmosphere relaxed and friendly. We decided to eat dinner here each night and the food was great - authentic Southern Italian dishes washed down with the local house wine.
Lunch was also excellent.
An excellent value for money gem.

the setting is reminds me of a greek island. very relaxing. basic rooms but very clean with a balcony overlooking the sea. the beach is tiny but the boat taxi is a terrific way to get back & forth to Positano. The staff are so friendly and charming, and the dinner is do delicious that we decided to eat here every night. We would definately stay here again.