Evening in Paris

It will take you awhile to get to your hotel and settle in. I'd suggest a taxi from Gare du Nord for that many people with luggage. I don't know of a walking tour you could do that evening, but Paris Walks has lots of excellent ones in the daytime and earlier evenings. Get some dinner if you're hungry, then walk over to the Eiffel Tower and watch it light up. If you're not too tired, maybe take a Seine cruise from near the Tower (but not for dinner unless you're in a hurry, the food won't be that good and you'll want to focus on the sights).

Don't worry about safety or sketchy areas, the touristed parts of Paris (and Rue Cler is very much so) are quite safe. Take precautions re pickpockets (lots of threads on this board, and advice on this website) and reinforce those with the young'uns. You'll have a wonderful first night in the City of Light!

Yes it really simply makes the most sense to get to your hotel, drop your bags, and walk over to enjoy the Champ de Mars/Eiffel Tower area. A perfect first evening in Paris! Find something to eat -- maybe even grab picnic fixings to have on the lawn -- and wander around and under the tower, and even across the river for the vantage point from Trocadero if you feel like it!

Fat Bike Tours offers an evening ride, if everyone are cyclists. There are also evening bus tours (but kids would probably prefer the boat). Rick's Paris book describes an evening tour you can do by private taxi, with directions for the driver and the freedom to make stops. See also the short article Paris When it Sizzles.