The Vatican tours were good. Their organisation wasn't. (CIT tours weren't part of the picture except the booking front end. All tours done or maybe finally 'arranged' by local organisation - "Seduction Tours" out of Naples / Amalfi. ) I booked Cit via my Travel Agent, not the web site.
I would recommend doing both tours - the first one took us through the gardens, which was great (and large) and hardly anyone else there. Then we did a tour of 'some' of the Vatican museums - they are huge! - and the Sistine chapel which was chokkers, with the general din being pierced by regular calls of 'Silence!' in several languages
The guide then showed us the 'short cut' exit from the Sistine (door at the far RH end from entry) where you can leave the Museums and get a short cut to the queue for the St Peter's dome elevator (or stairs). # We continued out of the Sistine and finished up in St Peter's cathedral which to me was an equal highlight to the Sistine.
The next day, our group of about 15 really was the very first group into the complex - amazing. We marched past about 8 or so groups of people in rope lines at the entrance who were also on 'early access' tours! But all they do I get you in, give you a bit of a map, and you are off by yourself. Because I was there the day before, I knew exactly where to go through the maze of halls etc and I think I was second one into the Sistine Chapel and there were still only about 5 of us there for 5 to 10 minutes. Fantastic to get a good look (sitting down!) in actual peace and non-crowded.
Organisation: Hopeless. Both tours were due to meet by the street steps on the opposide side of the street to the entrance. Trouble was, that's where ALL the groups meet, so there are people everywhere, even early. Our tour person on both days was late (not the same person as the guide). and no label or sign that I recall (unlike most of the other tours meeting there!!). The first morning, I managed to spot other similar frantic-looking people who I guessed were part of the same tour. I ended up calling the tour people and actually got some-one on their mobile, who said 'don't worry'. Yes, the organiser turned up and we actually entered on time and met our guide, but not very professional (but typical of Italy, I got to learn). The second morning, the early access one, the person was late again and no-one answered my calls. The person turned up at 7:44am for a 7:45 entry, so we just made it. :evil:
# The line to go up St Peter's dome is amazingly long, out around St Peter's Square and via 1 or 2 lots of security. If you take the 'tour group' exit out of the Sistine, you come out where the queue is about 15 people from the ticket counter, and there is a break in the line due to it being a cross-walkway; the rest of the queue is around a corner, and people are let through by a guard. Sorry if this appals some people, but it is Italy and it is the way to get to the Dome if you are already in the Vatican complex.
Big crush of people at the very top of the Dome but there are some nice ice-cream shops etc on the church roof before you head down. BTW you are allowed to take bottles of water etc through the museum complex - in fact there are vending machines in the arrival/ticket office where you first go in.
Tip: Whoever you book through, get mobile numbers off them and get them to re-assure you that some-one will answer, on the morning. Get them to tell you
exactly where on the steps you are to meet - top, bottom, right, middle or left or whatever. There is a decent coffee shop right next to the steps; open at 7:30am I think. Good for breakfast while you wait!
My Pompeii tour was a disaster, but I learned a lot about day tours. I booked 2 half days - pick up from Naples, tour the ruins in the morning, then go up Mt Vesuvius and return to Naples. Cit tours was just a front end. The tour was done by some local group and they 'aggregate' people from different tour bookings - no-one else in my group was from Cit Tours. During the bus pick up of hotels, the organiser was on the phone obviously arranging pick ups of extra people - we made a lot of non hotel stops. Got to Pompeii late, met the guide, invited to shop first while they waited for yet more arrivals. Get on with it!! Tour was shortened due to very late start. Poor tour.
Lunch (included) at a restaurant outside the ruins - fair dinkum, the absolute worst meal you can ever imagine - bulk produced slop. I and half the group ended up getting up and bought some fresh fruit. Afternoon tour also late as they stitched 2 tours into same mini bus - one couple going to a winery, the rest of us up Vesuvius. So we were late at Vesuvius after they dropped the couple off first. Its a bit of a hike to the crater rim where the vehicles drop you off, but very worth it - fantastic views from the top.
Tip: Pompeii: if you go via a tour, try as much as possible to ensure that you will be with the same group from start to finish, and they won't be adding other people or groups along the way. I think some sort of guide is important to truly understand the ruins. I got a tour that picked me up in Naples as I was short of time - if I wasn't so rushed I think I would stay locally.
Edit: I think half a day at Pompeii would be enough, as long as you start early enough - maybe 9am and finished maybe 1pm. there is lots there, but much fairly similar.