Stayed at the Marriott Central Park. Property is being refurbished but still very good. Rooms are excellent and they have a shuttle from the hotel to within walking distance to the Vatican. No cost but first come first served. It runs on the hour FROM the hotel and on the half hour back to the hotel.
Additionally, the hotel is a five minute walk to the train station at Gemelli. The cost is 1 euro per person to ride the train and the metro for a consecutive 75 minutes (a great deal). Be careful on any train in Europe for pickpockets. I had a guy in my pocket in Athens on their train system just two days earlier.
The train can get you to the Vatican, the Collosium, the Forum, Spanish Steps and Trevi Fountain plus many more major sites in Rome. The time from the hotel to the Vatican including the change to the Metro is approximately 20 - 25 minutes. Other sites are additional 5 to 10 minutes. Taxis or car service would run 35 - 45 euros around town.
The hotel wants 55 euros for transportation to the FCO airport. You can find local car service for 45 euros.
One negative for this property is thei esturants. They have two restuarants on prperty but as expected the food in just okay and expensive, Dinner runs qround 55 - 75 euros while breakfast is 13 euros per person. Breakfast is defintely NOT worth the price.