Bistros near the Arch de Triomphe
Bistro Flaubert (10 rue Gustave Flaubert 17eme) is approx 10 minutes walk from the Arc. It is run by Michel Rostang who has a Michelin 2 star next door (http://www.michelrostang.com/). The cooking is very good - it is small and so you must reserve, good value at about €130 for two with wine.
For lunch there is "Comptoir de L'Arc" (73 avenue Marceau 16eme), inexpensive and good - full of locals but not open weekends or evenings (to my knowledge).
But do avoid the "Champs Elysees" poor value and average food.