Champs Elysees is easy to see, it is only a big avenue. If you walk fast you can do the Louvre in a few hours. What about the Eiffel Tower at least? That's about all you'll have to time to do in one day, at a quick pace, in the evening walk along the Seine and enjoy the view, you'll see plenty of other monuments, the Notre Dame church, the city hall. The advantage of Paris is that it is a dense small city so most things are in walking distance. Then Disney for a whole day, cause you have a 20' wait for each attraction.
Lyon has plenty of hidden nooks and crannies to visit. You have the Church at the top of the cliff, with a beautiful view of the city, the old quarters with cobbled streets, corridors going through the buildings, old churches, the open air markets along the two rivers, the cable car to the top of the cliff, museums, the free range zoo, the park of the Tête d'Or. Of course there's less to see than in Paris but it is still a very beautiful city. And the food is great.