Newbie advice

Welcome!

I don’t know that you’ll find a “list” of that sort here in forum but a search for “Rome guide” will be a good start
https://search.ricksteves.com/?button=&date_range=1y&filter=Travel+Forum&query=Rome+Guide+&utf8=%E2%9C%93

When you search the forum be sure to filter by

Type-Travel Forum
Date-6 months, 1 year etc

The RS Rome or Italy guide books would include recommended private guides.

Good starting point
https://www.ricksteves.com/europe/italy/rome

It would be a challenge to hit all the highlights in one day. We used https://www.througheternity.com/ and highly recommend. One day we did a tour that included the Colosseum, Forum, and Palatine Hill, and the next day we did the Vatican tour.

Welcome to the forum.
Walks of Italy Rome has a full day tour. I have not taken it but took several Walks of Italy site tours on my first visit in 2019.
https://www.walksofitaly.com/rome-tours/rome-in-a-day-tour/

Another welcome to the forum!
Question? If you have 2 days, is there a reason you want to try and hit the "high spots" in a single day? And what would be the "high spots" for you personally?

Or do you only have two nights and one full day to explore? If it's only one day, the actual date may be important if one of the "high spot" attractions may be closed on that day.

It's really one full day and 2 1/2 days as we get mid day the 1st day and leave on our cruise mid day on day 3
I guess my highlights are the Coliseum, Forum, and squeeze in the Vatican

By "the Vatican" do you mean St. Peter's Basilica, the Vatican Museums (which include the Sistine Chapel) or both?

If that first half-day is the day you arrive in Europe after an overnight flight, I would be very, very leery of booking a tour for that time period, especially a costly one. Many people are brain-dead after the transatlantic flight from a combination of sleep-deprivation and jetlag. What could work would be taking one of Rick's self-guided walking tours. That would keep you outdoors and help convince your body it needs to start operating on European time.

Welcome to the Forum. Your trip sounds amazing.

I have been to Rome several times and have taken walking tours with Walks of Italy. While I have not done their full-day tour, I did some research for you and they have one called Rome in a Day Tour: Including Vatican, Colosseum & Historic Center. It takes you to the places that you are most interested in and comes with private transport to get you from the Colosseum to the Vatican. I have taken both the Colosseum Tour and their Vatican tour separately and the guides were very knowledgeable.

Hi there, If you just wanted to go take a look at St Peters, you could do that and skip the Vatican museum, if you want to see both and sounds like you only have one full day, agreed Walks of Italy would be your best bet. Even if you're young, your feet will ache by the end of that day, wear hiking boots is our strong recommendation, Rome has killer cobblestones. Maybe think about what else you want to do with your time. Rome is amazing, so much to do and see that's walkable, not necessary to go inside anything except some churches on that arrival day. But the day you're leaving departure is at noon from outside Rome, would be very surprised you have time to do much that morning unless you're very early risers.

(Agreed with Acraven, if you're just arriving from overseas into Rome that day, it would be very rough to do the long day Vatican City, Forum and Colosseum in one day, you will be blitzed!) Use the 'watch listen and read' button on the left and take a look at what else is in Rome, frankly instead I would do a nice long walk, longer lunch, siesta, and perhaps evening golf cart tour after dark on that day instead of trying to hit all those places, but there are no right answers, sounds like a great trip!