This is a local favorite for young couples and families alike. Their menu is very simple and limited to salada, pizzas and panninis, and prices are reasonable, ($10-$15). There are two locations, one in Polanco across the street from Lincoln Park and a newer site at Arcos mall in Bosques de las Lomas.
I like the Polanco location better because it has tables on the sidewalk and it's a great place to watch people go by and on a sunny day you will feel like staying there for hours. The block it's located on has door to door restaurants, any type of food you can think of and if there is a long wait for a table you can stroll next door and find another place to eat.
The Arcos location is in Mexico City's newsest high-end mall. There are a variety of exclusive boutiques (Steve Madden, Ferragamo, Marc Jacobs) as well as italian ice cream shops and cafes. There is a large multiplex theatre if you feel like watching a movie after lunch.