Hi Joel, welcome to the RS forums -
I've not had firsthand experience with a My Way but I'm kicking your post to the top of the list - thus making it more visible - to try and get you some feedback from those who have. :O)
There's really only one My Way tour for Italy so this must be the one you're considering?
https://www.ricksteves.com/tours/italy/my-way-italy
If you haven't already, browse the reviews in that link from people who've taken it? I see lots of positive comments regarding helpfulness and knowledge of the guides so I wouldn't worry about that piece. IMHO it is, however, a rapidly moving itinerary of, realistically, 11 sightseeing days + an evening on arrival day, and 6 hotels within that time Venice>Lake Como>Italian Riviera>Florence>Assisi> Rome. It's meant to be a sampler for the time-constrained or those considering longer stays/more in-depth exploration in the future.
Is it a good choice for your family? You are best to answer that question as you know how your tribe travels. Can everyone cheerfully get up and get going in the morning? Are they interested in the sorts of attractions/activities the locations have to offer? As well, if you're planning this trip during the summer months, how does your family handle heat and crowds, as you would be dealing with both?
Worth mention will be the need to reserve your timed-entry tickets to any of the most visited attractions you're planning to visit well in advance, so your "My Way" time would need to be somewhat structured.
As the itinerary provides just 1 full sightseeing day + some additional afternoon/evening hours in each location, I don't see where you'd have time for an overnight trip if it's in the middle of the tour. What you could do, however, is add days to the front and back ends to sightsee/travel completely on your own. You'd want to be in Venice before the tour begins anyway (a buffer in case of transport delays/cancellations) and Rome most definitely deserves more time. If the desired day trip is within reasonable reach of either, then sure, why not.
Does this help?