Lisbon itinerary critique please

You are smart to group the Jeronimos Monastery, Belem Tower, and Colonizers' Monument into one day, as they are near each other. Near the art gallery, as you walk between the Belem Tower and the Monastery, there is a very cool raccoon sculpture on the wall. Try to see that.

Your son might enjoy a lunch at the Chapitô à Mesa. It's a circus school that has a restaurant in it, and although I went in the evening, I've heard that you can watch the students practicing if you go during the day. It's in the Castelo district.

Also, are you planning to visit Sintra before or after Lisbon? If not, try to fit in a day trip there. It is easily accessible by train, and the Pena Palace and Moorish Castle ruins are very interesting. The streets in Sintra are even narrower than in Lisbon, too!

It was a while ago that I was in Lisbon, but, at the time at least, I found the Lisboa Card to be excellent value (unlike many city cards). It gave us free or discounted admission to many of the sights, as well as free transportation within LIsbon, to the airport and back, and to Sintra and Cascais. And, unlike many city cards, it gave us the full number of hours on the card instead of expiring at midnight. (i.e. If you start using it at 3 pm on the first day, it doesn't expire until 3 pm on the last day, instead of at midnight the night before.)

https://www.lisboacard.org

A hidden gem near the Jeronimos Monastery is the Maritime Museum if the Portuguese Golden Age of Discovery interests you. Not just educational, it is not crowded, it's a very large museum with interesting model ships and instruments that were used during those times.

Other than that, check to see if RS has an audio guide with a walking tour in Lisbon.

While you are in Belem, you might want to visit the Coach Museum, a collection of beautiful and elaborate historical coaches. I don't know how much your son likes museums, but it takes only about an hour. It's very interesting.

And at the Mosteiro de Sao Vicente de Fora, be sure to go to the rooftop for spectacular views of Lisbon and the river.

Thanks for the suggestions! I will look at adding these into the itinerary. We're hoping to fit in a Sintra day trip on the back end as well.