I have used Through Eternity in the past however, I have been advised to look into VIATOR. Your opinion?
Viator is a third party reseller
They don’t actually run any tours
Stick with the actual tour company- Through Eternity
Another company you could look into is Walks of Italy.
Who advised VIATOR? It is not a tour company.
Because of your post about Through Eternity Tours of the Borghese, you might want to check into the websites of attractions you wish to visit to see if they offer their own tours, as is true of the Borghese? Of course companies like Through Eternity, Walks of Italy, The Roman Guy, etc. can be good choices for tours which include multiple attractions, such as the Colosseum +Palatine+Forum, or the Vatican Museums + St Peter's.
Viator is a 3rd-party re-seller and do not operate their own tours.
Second vote for Walks of Italy - we did their Rome in a Day tour yesterday - great guide, well run & organized.
We've used Viator many times to book tours, with success every time.
In Rome we used ToursByLocals.com, and were thrilled with our guide Marisa, who is an archaeologist and led us on 2 days of tours all over Rome. I would highly recommend her, and we'll definitely contact her before we return to Rome.
We also did a food tour with a guide from theRomanGuy.com, and a tour of the Vatican Museum with another guide from theRomanGuy. Both were great and we'd use the company again.
My vote would be Walks of Italy for the early morning Pristine Sistine tour at 7:15 am and The Roman Guy’s 4-hour e-bike tours, both with RS discounts!