At Roscioli's, I go for the burrata and the pasta and skip the secondo.

Just down the street and around the corner from Roscioli's is Emma Pizzeria. (part of the Roscioli family) http://www.emmapizzeria.com/

And if you are in the area you really need to check out Caraphina gelato, it is a couple doors down from the Roscioli bakery on Via dei Chiavari