My husband and I stayed at Settimo Cielo about 7 years ago. It was adequate, as far as the room was concerned. In need of updating, but the pictures on the website look fresher than when we were there. The staff were helpful, and it has a nice view across the bay. Our balcony had room for only 2 chairs and a small table, but we enjoyed them. The breakfast was fine. The breakfast room has large windows overlooking the bay also, and there is a balcony across the front there. We sometimes went down there to sit outside at night. We never used the pool.
It is about a 10-15 minute walk to the center of town--downhill going, and uphill coming back, mostly gradual. The bay is within site as you do the walk, but in some cases you have to pay attention on the sidewalk, as it narrows and traffic is close by. We took a taxi from the train station upon arrival, but walked all the other times.
If your teens, or you, don't mind the walking, it's an affordable place to stay with nice views, and friendly staff (at least 7 years ago.)