The Avenue des Champs-Élysées is a must-see in the city of lights. Kind of sadly, it holds none of its former glory. What used to be a chic fashion district is now a whole lot of mall shops. There doesn't seem to be anything particularly French about it any more, and a handfull of overpriced tourist restaurants and chains like MacDonalds make it a culinary wasteland. It's not a place I frequent, but it does make for a nice walk if you have guest in town and want to see a lot in an afternoon.
Starting at the Arc d'Triomphe is a good idea since you get a nice gradual downhill walk.
There was beacoup huffing and puffing on the way up, as there are a lot of steep, narrow stairs to navigate to get to the top.
The Avenue connects a bunch of landmarks, so it's ideal way to get them all in.
A good tip: The Petit Palace is free to get in, and they have a really nice bathroom. A rarity in a city where most people (ahem, men) just tend to pee where they stand rather than be bothered with finding one.
The fountains at Concorde...
The Avenue ends at Concorde (where the infamous beheadings of Louis and Marie happened) and then you can take a stroll through the relative quiet of the Tulleries until you reach the Louvre.
If you've ever had the urge or need to by dozens of miniature eiffel towers, you are in the right place.