My wife Sarah and I are doing three days in Rome, but not the stretcher. Friends have told us about Viator Tour Company. (www.viator.com). They are a very reputable tour company, we've been told.
We are planning to book with them for a small group tour of the Vatican, probably on Saturday morning, 7/18. Check them out on-line, they have a variety of tour offerings in Rome, as well as other parts of Italy. They offer discounts for booking by 3/31/14. We also plan to book might do a day long, private car trip with them from Livorna, to Pisa and Florence.