I also have a 15-year-old and have been to Paris twice over after Christmas.
I recommend finding an Airbnb in Central Paris (1st, 2nd or 3rd arr.)... It is more expensive but if you only have a few days (and you will arrive jetlagged and exhausted on day 1).
Honestly, I would consider a hotel instead. You can find an affordable hotel and have the luxury of two bathrooms if you book two rooms for your family. For your first trip, it will be so much less stressful to arrive at a hotel and have an English speaking attendant waiting to greet you and answer questions. The logistics of meeting your Airbnb contact can be stressful - especially when you are sleep deprived. I prefer to be pampered and taken care for the first few days and then transition to an AIRBNB.
Taking the TGV to Strasbourg is very affordable (if you book exactly 90 days out) and only 2.5 hours. It is a relaxing an easy trip. The Christmas Market in Colmar looks like a lot of fun (I'm going in November), Here is a link to their site... https://www.noel-colmar.com/en/
Here are a few hotels to check out in Central Paris. They are are on the more affordable side and located in great neighbourhoods.
Relais Des Halles
Le Lapin Blanc
Hotel La Tamise
Hôtel Parc Saint Séverin - Esprit de France
Things to do in Paris:
Breakfast at Holybelly 5
Eat a Crepe at Creperie Dentelle
Eat Salted Caramel Ice cream at Berthillon
Take a cooking class at La Cuisine Paris
Take a River Cruise
Attend a concert at Église de la Madeleine
Marais Food Tour with Paris By Mouth
Walk to Montmartre
Dinner at Les Papilles (email to make a reservation)
Have a fabulous trip!