If you are going to DF for the first time, it might be helpful to get a simplified "socio-econo-geographic layout" of this massive overly complex metropolis. So I am going to translate DF into Angeleno because that is a city I know like the palm of my hand:
Here is a simple map with points of interest:
La Villa up near the top is where the Virgen de Guadalupe shrine is found... and you can think of this as the heart of Mexico City's blue collar, graceful poor part of town. The LA equivalent would be Montebello, Pico Rivera etc., this is your lower middle class... not rich, not cosmpolitan but not desperately poor either. Good food comes in the form of Tianguis, Rosticerias, Cenadurias & little corner stores & Cremerias.
Xochimilco is the big green area in the South - Southeast part of the map. This is a very indigenous part of town with many people still speaking Nahautl and the best place to find ancient Native cuisine like roasted or grilled rabbit, acociles (local crawfish), steamed trout, pulque, huitlacoche tamales etc., There is lots a decent food in the tourist part where all colorful boats are... but there are also a few Fondas serving organic ingredients grown within the Chinampa. See this for some pretty good insights:
UNAM is west-northwest from Xochimilco in the Pedregal region. That is where you will find Cafe Azul y Oro by Ricardo Munoz Zurita... THE man in Mexican culinary research. Also the area around UNAM... San Angel & Coyoacan are basically the Pasadena of Mexico City with huge old mansions, cobble stone streets, graceful parks that host art fairs, farmer's markets.... and generally play home to the bohemian, poor artist crowd.
From a food perspective... this part of town is home to a lot of the young professionals (and college students)... and many joints are geared towards meeting young people. Lots of bistros & sports bar type places... its very equivalent to the neighborhoods around UCLA, also home to some of the best Argentinian & Brazilian meat centric restaurants.
Secondarily... Coyoacan & San Angel are home to the 2nd tier wealthy people (just like Pasadena is in L.A.).... and this is where you find some nice, traditional haute restaurants set in colonial haciendas. Of the bunch I think Antigua Hacienda de Tlalpan is the best: http://www.antiguahaciendatlalpan.com...
The Zocalo is nearly in the center of the map... not far from the Airport. As you go west from the Zocalo and see the World Trade Center & Chapultepec.... that Blvd. is Reforma... think of it as the Wilshire Blvd of DF.... most of the attractive Architectural sites (sculptures, parks etc.,) as well as the Financial District, Hotel & Gastronomic Zones etc., are along Reforma and its off shoots.
The Centro Historico around the Zocalo is the home to the best traditional bars, Mercado La Merced, Mercado San Juan, Parque de la Alameda (birthplace of the bacon wrapped hot dog) and of course the Templo Mayor ruins & museum... this was literally the heart of Tenochtitlan. The place to hit is Bar La Opera, Fonda de Don Chon (temple of insect dishes) and lots of great street food all over including branches of El Tizoncito (the place that invented Tacos Al Pastor) & Pozolcalli (chain devoted to many styles of Pozoles) etc.,
> The area west & northwest from Chapultepec is the real high end part of town. If you have watched the film Man on Fire... this is where the girl's family lives. Within Polanco you will find Avenida Masaryk... very much equivalent to Rodeo Dr. and home to Izote and other high end restaurants.
Ciudad Neza is the part of town where the big Rave takes place in Man on Fire.. you can see it on this map its East of the Zocalo & Airport...
... if you have watched Amores Perros... this move ends on the industrial edge of Neza... its a surreal place that used to be devoted to agriculture... but with the mass emigration to DF from the Ranchos in the 1950's the government went in & built a very dense, grid dominated slum with no parks. This is ground zero for Naco lifestyle.... life is so dreary & congested there that people become incredibly creative with the little real estate they own... namely their own bodies & ideas... lots of tatoos, crazy hair dos, Rage Against the Machine t shirts, crazy culinary inventions using processed foods & semi cooking etc., The best analogy is South Central & South L.A.
The areas north of La Villa are pretty neat... most are Aztec villages with ruins & the whole spiel that in the 1950s were seperated from the City by forests & countryside... now they have been swallowed up by industrial parks, grey concrete housing projects & haphazard urban growth... but they still retain their charm with colonial buildings, cobblestone streets, ancient ruins... and lots of people that speak Nahuatl, Otomi & other languages and have interesting food traditions.
Cuauttilan Izcalli & Tenayuca are the biggest draws.
Back to the Center of town.... as you go from the Zocalo to Chapultepec there are a number of areas along the way including Roma, Condessa & Zona Rosa. The Zona Rosa was the tourist area back in the 60's & 70's... its now a bit cheesy & outdated, and just starting to update.
Condessa & Roma is where its at... with some drop dead gorgeous urban neighborhoods... 1920's Art Deco buildings, narrow cobblesone streets lined with lots of trees.. lots of little make out alleys, upscale & chic hotels, restaurants, bars & clubs, art galleries & museums.... this is the part of town you can stroll around with the sig other. A
couple places to hit there for a few drinks:
In Polanco there two standout bars... one is inside the Camino Real (hotel designed by Ricardo Legorreta)... Bar Azul... and the other is the rooftop bar at Hotel Habita.
So what is special about Mexico City street food (in addition to things like Tacos al Pastor, & Huaraches that have already been covered Ad Naseum?
> Tacos de Fritangas.... these vendors have cauldrons bubbling with manteca used to cook all kinds of offal... this is the place to sample tacos de Rinon, Corazon, Machitos etc., everywhere you see a grouping of street vendors there is bound to be one of these. In Xochimilco and points south... you are more likely to find Fritanga vendors that specialize in things like Frog Legs, Crawfish, Freshwater shrimp etc.,
> Tacos de Canasta... you will see guys on bicycles, with baskets on them selling you the dumpling like steamed, folded tacos
> Quesadillas de Comal... made from fresh masa & stuffed with things like Huitlacoche, Flor de Calabaza etc.,
> If you encounter a Tianguis look out for the Potato Chip & Donut fryers... pretty great stuff straight out of the lard.
> Tacos de Guisados... again there should be at least one in every grouping of street vendors.... serving up a dozen guisados, ladled over a corn tortilla & a layer of rice (to prevent the taco from falling apart)... true Homecooking housed in edible, convenient, urban packaging.
> Licuados & Agua Fresca vendors inside the Mercados... we are talking places with 25 to 50 types of Agua Fresca "on tap" and a huge variety of Licuados, Eskimos and all types of milkshakes & smoothies.
> Rosticerias... fantastic rotisserie, tortillas, salsa & salads to be found in all the blue collar neighborhoods.
> Cremerias... this are places are basically Mexican delis that specialize in Cheeses, Embutidos (the Mexico City term for Charcuterie), and great variety of preserved, savory foods. They usually offer snack foods as well such as Pig Feet tostadas topped with Artisinal Cremas & Cheese, Headcheese sandwiches & little rolls of deli thin Ham rolled around cheese & strips of house made Jalapenos en Escabeche.... maybe some green olives on the side etc.,