Commas with Items in a Series

Use commas to link more than two items in a series, as shown here:

I decided to change jobs for tax cuts, job security, and pay equity.
The ways to change legislation include discussion, protest, and disobedience.

Which sentence is correct? Her itinerary included stops in Milan, Florence and Naples. On their way to the train station, they stopped to buy film, maps, and snacks.