My college daughter and I did the Amalfi AE in May of 2023. I had been to Italy a few times before. This was her first trip. Regarding your question about the private Vatican tour - yes, there are other companies that do that specifically. But there is only one per day, and not done every day, so its quite limited. Prior to the Amalfi
ABD starting, we spent 5 days in Rome. One of the things we did was the VIP Vatican Key Master's Tour: Unlock the Sistine Chapel. It started at 6 am (we were there at 5:30 and watched the sun rise outside the Vatican). We were the only visitors inside the Vatican, and there were very few workers/security. We were a group of 20. Everyone unlocked at least one door. I personally opened the envelop containing the key to the Sistine Chapel (it is separate from all the other keys on the key rings) and then opened the Sistine Chapel for the first time that day. And everyone got a chance to hold the key and unlock the door later. Turning on the lights at the Gallery of Maps was incredible. We also went to the Bernini staircase, but that's not a guarantee. Our tour ended around 8:15, at which point we could start to hear all the commotion from the people inside waiting to start their "early entry" tours. This is by Walks - their former name is Walks of Italy. Walks of Italy is easier to google and will get you to their website. You can see their reviews for this tour online, which are uniformly outstanding. It came into being due to a very unusual and special/privileged relationship between the owner of Walks of Italy and the Vatican. (I found out about this on another Walks tour we did) Other companies do it, too. You can search for Key Master Vatican or Clavigero tour. Also - there are also companies that do after hours tours, which is what I think ABD now does. These have much more availability. There will likely be a few similar tour groups in the Vatican at the same time, so you'll hear other people, and maybe see them, but nothing like the tens of thousands during the day. You may or may not be the only group inside the Sistine Chapel - it all depends........We did 5 days in Rome, then took a private transfer from Rome to Sorrento, spent a day on a private tour (Agri turismo and Amalfi Coast drive) near Sorrento, then did the ABD. On the trip from Rome to Sorrento we did 2 stops. One in Herculaneum, and one in Naples, I put together the pre ABD itinerary based upon what I wanted to do plus looking at other itineraries I had heard about primarily from different podcasts. In Florence, we did skip one day of the ABD tour and spent it in Florence to do more shopping and more art. While at breakfast that morning, we saw probably 4 other groups who also skipped the ABD tour that day, ha. So, there is some flexibility. Even with skipping that day, the ABD is worth doing. We loved this trip! Both the things we did on our own and the ABD portion. So, all of this to say that, yes, I do think that its possible to create both the Italy ABD and the Amalfi ABD, on your own, with similar service levels for much less. But - it would be a lot of work, plus do you want to spend your vacation being a tour director for 2 weeks - because things always go wrong, and I think you would still need some first-class tour operators. No way it could be done by stringing together independent tours from Viator for example. Plus, the people on our ABD were so much fun to travel with! Good luck!