We, two couples, are coming to Ravenna in September after the cruise and need to get to Venice. What is the best way to do it?
You can search on Trenitalia to find the routing that fits your schedule best, but the quickest way is a regional train to Ferrara, then change to a Frecciarossa to Venice. Regional trains the whole way is slightly cheaper but slightly slower, still with a change in Ferrara.
The cruise is likely to have charter buses arranged (for a fee) to get to Venice. Probably everybody on the ship wants to go to Venice. Cruise ships are not allowed in the lagoon anymore.