what to do in Rome on our extra day after our 14 day BOE trip ends?

You could get out of town and see Castel Gandolfo. Go to the Papal Palace and have a nice lunch overlooking the lake. Not a big day but pleasantly laid back and allows time for your evening food tour.

You might want to check out Ostia Antica. Close by, accessible by public transit, not crowded at all, and excellent ruins. Google it and see it holds any interest for you.

You could enjoy some time on the beach at Ostia Lido, although it could still be busy on a hot Saturday in early September. Ostia Antica is along the way to the beach, should you wish to visit. Other non-museum options include a visit to the Appian Way, a walk/bike-ride in the Villa Borghese park (a lot of the park is shaded by trees), or a walk through the Trastevere neighborhood which tends to be a lot less crowded during the day.

IF you have already seen the Vatican, Pantheon, Coloseum & Forum, and walked through the famous squares . . . we did 2 GREAT walking food tours 'off the beaten path' through EATING ITALY - go to their webpage- we enjoyed both of them as they were in different Rome neighborhoods, but very different too. You can also see photos and read reviews on TripAdvisor - but I'd book directly on Eating Italy webpage.

You're going to love BOE14 - we found it the perfect blend of EUR city culture and pastural countryside charm, with one historically-significant site visit after another. It's amazing how much they pack into these two weeks! As you're aiming to do, we took an extra day in Rome (after the tour concluded), and spent it in Trastevere. Enjoyed the area very much, across the Tiber where time slows to a crawl:

https://www.lonelyplanet.com/italy/rome/trastevere-and-gianicolo/travel-tips-and-articles/a-perfect-day-in-trastevere-romes-favourite-neighbourhood/40625c8c-8a11-5710-a052-1479d277b005

Have a great trip!

It doesn't look like your tour covers the Borghese gallery and gardens.

I could only find the Italian website

http://galleriaborghese.beniculturali.it/it

This is the official ticketing source for the Borghese:

http://www.galleriaborghese.it/en/home_en/borghese-gallery-and-museum

You might think you've had enough museums but this one is a rare gem! The collection and the building it is housed in are magnificent, and it has excellent crowd control...unlike the Vatican. You have to choose a 2-hour time slot, and the galleries are cleared between each slot so only a set number of visitors can access it at one time. HIGHLY recommend, and pre-reservations are mandatory. The huge park (Villa Borghese) the museum is located in is a pleasure to walk as well. There are a couple of cafes for resting feet and having a beverage (adult or otherwise) and a snack or meal along the way.

On the far western end of the park are the Pincio Gardens with a really nice overlook of Piazza del Popolo and some of Rome. Walk down the stairs to the piazza and visit Santa Maria in del Popolo church with its many works from notable artisans.

http://www.060608.it/en/cultura-e-svago/luoghi-di-culto-di-interesse-storico-artistico/chiese-cattoliche/chiesa-santa-maria-del-popolo.html

We woke up that morning and decided we wanted a relaxed day. At the suggestion of our guide at the tour end breakfast, we ended up downloading Rick Steves Rome - Jewish Ghetto tour and Rome - Trastevere walks and did both. They both happen to start at the same point on a bridge in the middle of the Tiber River. We did the Jewish Ghetto tour which is short especially since it was Shabbat and the Jewish Museum was closed, and then we backtracked and did the Trastevere. I highly recommend the Trastevere tour - loved the back alleys and the 2 churches on the the walk were beautiful - we even got to crash a wedding at Saint Marie in Trastevere. It finished in an area full of restaurants. Again, at the suggestion of our guide, we went to Dar Poeta, for pizza, which is a few blocks away from the end of the walk on a small alley - and not filled with solely with tourists.

We returned to Da Francesco for dinner (recommended by one of our local guides) and spent the rest of the evening strolling by the highlights of Rome (great view of a lit up St. Peter's Basilica from the plaza in front of Parliament).

Thanks for the suggestions. We loved Rome and plan to do Ostia Antica, Borghese and some of the other suggestions next time.