Itinerary advice for France, please! :)

Something for you to focus on in your trip research is: the travel time between Paris and Nice, and how that fits in with your objectives. You're the best qualified person to determine that.

The two teens will really only have 6 full days, and since they are flying in and out of CDG, I would stay in Paris, even though your daughter has already been there (although I cannot imagine she would be bored with that city!). Too much travel time to Nice and back for such a short stay. Since you've never been to Lyon, wait till the teens have left; you would waste too much of their short time getting oriented. A day trip to Versailles and another to Chartres or Fountainebleu would be easily doable by train or even bus if Paris doesn't hold enough for them (impossible!) or they just want to see a smaller town (understandable). I like nearby Giverny, but January would be the wrong time.

Right now I am thinking of going:

cdg to lyon (1 and 1/2 hours by train)
-- stay two nights
lyon to nice (approx 4:40 by train)
-- stay two nights
nice to paris for the rest of the time.

This is still a rough plan...trying to figure out the best way to do this.

Thank you goodmanTX -- I just saw this after I posted last. I need to give them that information. It is a lot to do. They do arrive at 6 am on the 20th, so I was going to use that as a slow day, but still seeing places.

You are correct, we certainly don't mind being in Paris again!

I wouldn't travel all the way to Nice for just 1.5 days, even aside from the fact that you'll have a 6-hour return train trip to Paris (or perhaps 5+ hours dealing with airports), which pretty well destroys one of your Paris days. There are better options for 2 nights than Nice, because Nice is partly about seeing nearby places like Menton, Eze, St-Paul-de-Vence, Antibes, etc.

Lyon is great though, and very feasible.

Nice is, uh, nice, but not spectacular and not worth going the distance in so rushed a visit. Ditto Lyon, without the pun. By taking a Paris newcomer, you are almost obligated to concentrate on that city. As you know, there are plenty of possibilities for day trips. You, and your daughter for that matter, can wander further afield while the newcomer explores on her own, prepping for her subsequent visits. It's okay to expect them to take adult responsibilities too.

Skip Nice - too far for what you'll get (esp in January). Unless you are a true foodie with an adventurous palate, I'd skip Lyon, too - the culinary scene is the real draw there, imo.
If you think Paris will get old in six days (lol), plan a day trip somewhere out of the city but spend your nights there for such a short period.

Thanks for your help...I am also thinking it’s too much to go to nice. Day trips are probably a better idea. I think I’m going to spend time looking up worthwhile day trips.

I love Lyon. It’s a beautiful and walkable city. People are very friendly. Great food. Great sites. If you like wine then Kanpai does great tours. Highly rec the Beaujolais cru tour. I stayed in the most amazing air bnb there. PM me if interested.

Took my daughter to Paris for spring break of her first year of college -- and we found plenty to do for a week. There are no doubt museums and sights you have not visited on earlier trips, or wouldn't mind seeing again.