I'd definitely like to add Les Halles in France to the list. This place is an absolute must-do for us with every visit. I'd recommend it for lunch as it they don't really have entrees per se, but they do have fabulous sandwiches and savory items and their pastries and desserts...and oh my are the desserts fantastic.
If for no other reason, go for the large range of sweets--our favorite are the domes and the mousse, but our absolute faves are the box of various macarons...OMG it is ALL delicious. Possibly save this to have before Illuminations or something if you are wanting food from a different QS place.
(Someone earlier mentioned Boulangerie Patisserie, and that is what it used to be called before it became Les Halles Boulangerie Patisserie). Due to the popularity under its previous name, Les Halles was moved to a larger location and has both covered and outdoor seating available in the French area. The interior kind of reflects a French market--it's nice, but I'd definitely recommend getting a quieter seat outside of the busy area over at the benches by the water overlooking the International Gateway entrance and enjoy your goodies these.
Do not miss Les Halles!