Ristorante Bagni Delfino is located in the Marina Grande in Sorrento; unlike the name would suggest, it's a small but very picturesque marina. There are several other restaurants, but I think Delfino is the best one. Make sure to make reservations in advance!
You can either go for lunch and relax afterwards on one of the sunbeds on the bathing platform, or like I did, go for dinner and enjoy a more romantic atmosphere. Just take a look at my photos... here a picture is really worth a thousand words!
Ristorante Bagni Delfino serves -of course- wonderful seafood, such as sea bass, sea bream, oysters, clams, mussels, lobster and pasta alle vongole, but don't worry if you or your travel companions don't like fish... they have a mean steak and delicious vegetarian options as well. Think Caprese salad, ravioli, gnocchi, melanzana alla parmigiana (a sort of eggplant lasagna) and more.
To finish in style order a glass of Limoncello, a local lemon liqueur traditionally made with the zest of Sorrento lemons. After that, a small walk is in order, but to go back into town I'd suggest you order a cab. (It's a pretty steep and long walk up the hill...)
Ristorante Bagni Delfino
Via Marina Grande 216
Tel. (+39) 081 878 20 38