Ok some quick notes. I'm in CDG presently having just left Rome. I booked with Hotel Tritone but got walked to their sister hotel, Hotel White which is up a level (4 star vs. 3 star) and more convenient to Barbarini plus off Via del Tritone which helps with the noise. The cost was the same, 400 Euros which was nice given that the going rate for Hotel White was at least 30-40 Euros higher on Booking.com I believe.

The hotels operate as a chain with their third hotel, Hotel Accademia which is also 3 star and the website is www.travelroma.com. I highly recommend Hotel White especially at the price point I got. They have free slippers, real key cards (no key drop-off) although you still need to insert the card to turn on the electricity. Toiletries are restocked daily and towels are changed daily as well. There's an in-room safe, mini-bar, laundry service and pant press. That's for the basic rooms. I think they also have more lavish rooms of course. The tub is very, very narrow so if you're slightly more wide think carefully before booking however.

Breakfast is included and great. It runs from 7am-10:30am and is well worth getting up for to off-set some of your food costs. The adjoining pizza parlors are decent for places so close to Trevi. The sell-by-weight place is pretty good and there's a supermarket out the door to the right at the corner.

The Cotral bus worked according to plan. I reiterate the other poster's suggestion to find the stop in the day time. The sign is not very apparent even with the prior directions to look in the 10 o'clock direction. Look parallel from The Route 38 island to the left and you should see it. I'll try to post photos of everything later.

Taxi from near Trevi to Termini cost me 10 Euros, the bus itself was 7 Euros and the trip took under 30 minutes. The bus did appear only 5 minutes after the posted time so don't allow yourself a buffer. The bus only stops long enough to pick up passengers.

There's food upstairs in the airport which is open at 4:30am before the AF check-in opens. LH is already up and running as is KLM but the French can't quite seem to get things together in the morning.