We are looking to go from Venice down to Bologna and then over to the eastern coast and return to Venice. Any suggestions on places to stop and linger?
Verona, Vicenza, Modena, Padova, Ferrara, Ravenna.
Some of those and also Cremona.
San Marino, San Leo, Rimini. If you have enough time maybe consider going a bit further south and visit Urbino and the grotto di Frassasi. If your planning to drive the coast back up to Venice ( I wouldn't recommend it but if you are) the Abbezzia di Pompossa is right off of E55 and is a really cool sight. Very small, you could see it in an hour or two. Also, I never stopped there but it was recommended to me, Comacchio which is supposed to be like a mini version of Venice.
Agree completely with Ron. We have family there, and our first two visits to Italy were taken on advice of relatives who live there. Exactly these cities! We loved them, especially San Leo. Our family is in Riccioni which is next to Rimini, and we loved this also, it's a fun little beach-town which we enjoyed. All of the beach-goers at that time were Italians. No Brits, Germans, Americans. Pretty refreshing!