Another vote for Senigallia. We visited in October years ago, staying at Hotel Palace. We did not have a car so this hotel was perfectly situated, an easy walk from the train station, restaurants, the beach … too cold for swimming but a lovely miles long stretch of sand if you like walking by the sea. It was a very comfortable hotel with sea-view balcony & breakfast & very reasonable price … not sure if they’re still open in November but worth checking.
Senigallia has great restaurants, including two with Michelin stars. It’s a very walkable town.
From Senigallia we took a bus to the 14th century walled hill town of Corinaldo. Nearby also are the Caverns of Frassasi.