We were there at the end of November with DS 23.
If you want to go to the galleries, book in advance as you will otherwise spend a long time queuing. If you want to see anything in particular, check in advance as both the Louvre and Musee d'Orsay had closed areas. If your DC has a European passport, by any chance, it's free for under-25s!
We bought a deal which included a bus tour, boat trip and top of the Eiffel Tower which was well worth it. Try to sit at the front at the top of the bus to get views of the lunatic driving around the Arc de Triomphe. Make sure you're well wrapped up for the boat trip as it can be freezing with the wind. If you get a ticket to the third floor of the Eiffel Tower, do that first and work your way down the floors, as the lifts from the top get full later on and you end up having to run down the external stairs if you have an appointment to keep!
We stayed in Montmartre which is lovely and safe, with lots of restaurants, but do not engage with anyone collecting signatures on clipboards around the church as they are scammers (they also have them at the Eiffel Tower). Do not bother with the Moulin Rouge.
Visit the Galleries Lafayette for the experience- the main women's dome building has views over Paris and also has a second-hand section which is well worth a rummage.
Although Notre Dame is still being renovated after the fire, it is well worth going to see the damage and there is a fascinating exhibition about the reconstruction on the fences around the site.
To get around, I would recommend getting a 10-journey Metro pass which you can top up if needed.
Enjoy!