Excerpts from some notes I typed up for a friend after we went in I think 2017:
We flew from DC to QC around 1 on Saturday. Got checked into our B&B (near the old city) and dropped off our stuff before taking off to explore. Came back and rested for a bit and then went to the "lower town" for dinner at Cochon Dingue. We ended up being a bit rushed to finish up and see free fireworks over the river at 10 pm. Info about the fireworks:
https://lesgrandsfeux.com/en/
Sunday we went to the Citadelle for the Changing of the Guard at 10 am. It was really neat to see but we were baking. It was on a huge asphalt parade ground and it was probably 85 at 10 am. Then we toured the Citadelle and headed to lunch at a burger place (Chic Shack). Did a fun river cruise that afternoon. We wanted an earlier night so we went to the great deal prix-fixe offered before 6 pm at Aux Anciens Canadiens - worked out really well.
Monday we wandered around the Plains of Abraham and then came back to the Citadelle for a tour of the Governour's residence. That was a neat tour. After that we wandered around, had lunch, happened upon a musket firing demonstration, etc. We had drinks at L'Oncle Antoine and dinner at La Pizz.
Tuesday we took the bus to Montmorency Falls and hiked around there for a while. Ubered back. We went back to the Farmers Market for lunch and then went to the ruins of the older chateaux (in the walls of the fortification). We went to the free circus that runs Tuesday-Saturday. It started off kind of "artsy" but was fun to see their acrobats and such.
The next day we took the train to Montreal for a few more days. That was about the right amount of time to do Quebec. My kid was a little younger, probably 7, hence the comments about needing earlier nights, etc.
It's a neat city - have fun!