Funny. Unlike, say, Chacun son cinema, the several shorts comprising Paris, je t'aime have an overall coherency, its individual segments feeling like aspects of a whole. Not sure just what it is that binds them all together, except perhaps the obvious, Paris itself; it's an impression aided, no doubt, by the relative lack of 'auteur' tendencies in the directors of the various pieces.
A few that stuck in my mind: Gus van Sant's "Le Marais", in which one young man haltingly-eloquently wonders to another, a stranger, if they might be soulmates, all the while unaware that the other understands very little French, is pleasingly wry and ends perfectly; Alfonso Cuaron's "Parc Monceau" (Nick Nolte and Ludivine Sagnier both note perfect) is just very appealing; Olivier Assayas' "Quartier des Enfants Rouge", despite being about nothing in particular (actress Maggie Gyllenhaal scores some drugs. The end.) somehow lingers (maybe it has a sort of infraordinary thing going); liked the Bob Hoskins/Fanny Ardant one, too, for the opportunity to see those two playing off each other; also, the one with Emily Mortimer was pretty good, though mainly because it was the one with Emily Mortimer (mind you, Oscar Wilde's showing up didn't hurt either); and the Elijah Wood vampire one, while OTT, was kind of cool (I didn't much like the other notably quirky one, the mime love story, though).