Rome/Sorrento

https://community.ricksteves.com/travel-forum/italy/help-with-17-days-itinerary

https://search.ricksteves.com/?button=&date_range=2y&filter=Travel+Forum&query=Sorrento+hotels&utf8=%E2%9C%93

Hopefully the above Searches have some useful info regarding the Sorrento/AC area, and the realities on the ground in the area. It's a frequent topic here. When is your adventure?

Have a great trip!

Two days is sufficient if that is all you plan to do in Rome. First day, you will be tired. Stroll around, taking in Trevi, or any other sites you would like. Book the early morning tour on your second day of the Vatican (Walks of Italy Pristine Sistine tour, they can also do the Colosseum as well.) That gets you the two highlights you mentioned. That is about all you will have time for based on two days.
In 2024 the Vatican will be opening at 8 am instead of 9 to the general public so that could change things for you.

See this post
https://community.ricksteves.com/travel-forum/italy/vatican-early-morning-tours-2024

Very nice, centrally located hotel in Sorrento:
https://www.hotelantichemura.com

It's just a couple blocks from Piazza Tasso and a flat, easy walk from the Circumvesuviana train station, restaurants and shopping. You can take a public bus (small fee) down to the Port of Sorrento (Marina Piccola) to catch ferries around the region, use the public lift (very small fee) or just walk (we did.)

https://www.sorrentolift.it/en/
https://www.sorrentoinsider.com/en/e/getting-around-sorrento-italy

The center is not all that large; we didn't need to use public transit at all although I'm pretty sure not every visitor would enjoy the puff up the cliff from the port below! HA! IMHO, absolutely it makes sense to base there for the sightseeing you're planning on doing. Ferry schedules are currently only showing the reduced winter routes so if your trip is later this year, keep an eye out for seasonal updates.

Yes, two full days are fine for the two attractions in Rome you're wanting to see; just be careful if one of those days is a Sunday when the Vatican Museums are closed. ALL advance tickets (or tours) for both the museums and Colosseum are timed-entry, meaning you'll have a specific time to be at the designated entrances for admittance. No one skips the security check queue at either attraction so the "skipping" advertised means only long ticket-purchase lines; it's a marketing thing.

Tickets and tours available on the official websites sell VERY briskly once becoming available due to their attractive pricing:

Vatican:
https://www.museivaticani.va/content/museivaticani/en.html

Colosseum/Forum/Palatine:
Current official ticketing site (this could change soon to a new vendor):
https://www.coopculture.it/en/city/rome/

This is the official information website for the park (Parco archeologico del Colosseo)
https://colosseo.it/en/

It's usually only active during the hours the attractions at the park are open, and it's been really wonky today for some reason; they might be doing some maintenance on it.

Palazzo Jannuzzi Relais Hotel, located directly on Piazza Tasso. We have stayed there several times, great location, and wonderful people who run the hotel. We like to book one of the 3 rooms at the front of the hotel that each have a large terrace overlooking Piazza Tasso. Lively area but quiet inside the rooms. It's very easy to get to Pompei, Capri, and Positano from Sorrento.

The train (and bus) station is about a 5 minute walk from Piazza Tasso. You can pick up the Circumvesuviana train there, which will take you to Pompei.

You can also pick up the blue SITA bus in front of the train station to go to Positano (tip: get an early bus for a better chance of getting a seat on the bus, then take the afternoon ferry back to Sorrento - it can be crowded and tough trying to get on the SITA bus in Positano in the afternoon for the trip back to Sorrento).

We did a whirlwind visit to Rome! We knocked out the Colosseum and Forum the first afternoon. The next morning took a bike-taxi from the Colosseum for a 30 minute ride to the Victor Emmanuel, Pizza Navona and the 4 rivers fountain and ended at the Pantheon. We ate lunch at a small cafe recommended by our bike-taxi driver in his very broken English ("no touristo!"). From there we walked across the Ponte Sant'Angelo because I wanted to see the angel sculptures up close! Easy walk to Vatican City from there. We had a timed entry to the Vatican museum/Sistine Chapel, the line waiting for tickets wrapped all the way around the building. We were almost an hour early and they let us in. We used the RS audio guide and we were able to exit through the side door and spent the rest of the afternoon at the basilica. By then our feet had had enough so we caught a taxi back to our hotel. It was a whirlwind 2 days, but we felt like we got a good start on Rome. We have since been back twice and end our trip in Rome the afternoon before our flight home the next day and have been able to check off some of the other sites on those trips (the Trevi Fountain was closed for repair on our first trip). Rome was at the end of our trips, so we were recovered from jet lag, but you should be able to see a few sites on your first day before you crash!

We stayed at the Hotel Bristol in Sorrento. It is up the hill, but the view was worth it - the entire Bay of Naples and Mt. Vesuvius in the background! We would easily walk down and occasionally take a taxi back up (we are in our late 60's). I would stay there again.

Glad you have such happy memories of your trip, Gigi! I'm not sure how long ago you visited the Vatican Museums but things may have changed since then due to the increase in tourism. For example, I wouldn't expect them to admit visitors with advance tickets much before their appointed time slot, and the inside passage from Sistine to basilica has been reserved for tour groups for some time now, and I'm not even sure that those which don't specifically include the basilica are allowed through.