I hate to break it to you, but there are lots of interesting destinations in Italy Rick doesn't cover because the publisher has told him he cannot add any more pages to the book! Even when you've been to every place in the book, you have more work to do. And there's an entire separate book for Sicily!
I don't plan trips to entire countries when the countries are sight-rich like Italy. I just try to cover some regions, ideally regions that aren't too far apart. Any given trip might include my priorities 1, 3, 5 and 6 because that grouping makes sense geographically. That saves time (so I can see more) and money. If I have less transportation expense, maybe I can afford to stay an extra day or two.
Last fall I wanted to attend a special event in Venice (where I hadn't been for 30 years), so I added on 3 nights in Padua and 3 nights in Ravenna. I had been to the latter two in 2015 but had felt rushed.
I decided this winter I could go to Rome and see a lot of the indoor sights even if the weather wasn't great. (It was generally fine except for the easy-to-anticipate short days.) So I added a week in Naples (day tripping to Pompeii and Herculaneum) and four nights in Salerno (day tripping to Paestum and Eboli). Because I wasn't traveling very far, I took less expensive (and slightly slower) InterCity trains rather than Freccia trains between Rome and Naples.
I will probably return to Venice in 2024 and will venture to a bunch of other interesting places in northeastern Italy like Treviso, Udine and Aquileia.
The Dolomites are lovely. There are some very nice cities and towns in the valley through which the rail line runs (Bolzano, Bressanone, Chiusa), and nearby Merano sounds worthwhile. You'd probably pass through Verona on the way to the mountains. Then you have Vicenza, Padua and Venice right on the rail line heading east from Verona. In the other direction you have Milan and--on a secondary rail line--Bergamo.
I have been trying to get to Turin for a long time but haven't made it yet. I try very hard to focus on what it's practical to see on each trip rather than on what is being postponed.