MGR's earlier warning about the dangers of Mexico City should be heeded as should the recent British Foreign Office's decision to push the city up the world trouble spot rankings [Mexico City is now second only to Bolivia for kidnappings in South America]. That said, if you've got your wits about you, don't do anything stupid and have enough Spanish to get by, you'll have a terrific time.

Some specific hints and suggestions based on my short time there:

Transport
Although the airport is centrally-located, seriously bad traffic in the city means it can take you up to 1.5 hours to get from there to most of the major hotels in downtown. Common sense dictates that you should avoid anyone touting for taxi business (as tends to be the case in any city). Head for the booth which has a logo of a plane on it just outside the arrivals customs hall. I was charged USD 23 for my transfer from the airport to hotel [downtown], no idea if this is the going rate or a special price for gringos

As for getting around the city while you're there, well that depends on your knowledge of Spanish, how much time you've got and your sense of adventure.

Most of the hotels advise you to take only the taxis they supply, although this supposedly means guaranteed safety it does come at a cost: a prix fixe at roughly double what any other taxi would charge you.

If you intend hailing a cab on the street [and you do so AYOR], avoid the green and white VW Beetles. I found the red cabs more reliable both in terms of honesty and drivers knowing where they were going. Before getting in, first check that the licence plate matches a number displayed on both the roof and the window of the car. Next ask your driver if he knows where your destination is. Also write down the number of the car in case of any subsequent complaint.

I rode both the subway and the little minibuses that tear down city streets, making sure to first conceal anything which might prove tempting to hoods, such as my watch and camera. Both modes of transport aren't recommended for the feint-hearted and I gather that muggings are particularly common on the subway.

Where to stay
I can wholeheartedly recommend the Camino Real (http://www.caminoreal.com/english/index.html) - the smartest joint in town and a member of Leading Hotels of the World, but this will depend on your budget. The place was built in 1968 for to house Olympic athletes and you feel like you've walked in to a Pierre Cardin catwalk show, circa late 1960s. Ask for a pool view room - these should be bookable via http://www.lhw.com/ for around USD 215 per night.

What to see
Again this will depend on how much time you've got and your spirit of adventure but my recommendations are:

National Anthropological Museum - like walking in the the UN Building in NYC with the added bonus of a stunning collection of pre-Hispanic artefacts
Correo Central - possibly the smartest post office anywhere in the world
Mercado de Sonora - bursting with colour, not to mention black market goods and witchcraft paraphenalia. AYOR!!!
The Cathedral - dominating the main square of the Zocala, across the way from the National Place and bang in the middle of the historical centre
The Palace of Fine Arts - whether what's inside floats your boat or not, the art nouveau building which houses the collection is a gem, as is the 1930s interior
The Latin American Tower - you'll feel like you've just stepped onto the streets of Midtown Manhattan circa 1955
Chapultepec Park - comes alive on a Sunday when families gather to do the passagiata. Also the place to see the volodores flying ritual
The barrios of Tianguis, Zona Rosa [many dining options here], Condesa, Romoa and Coyocan [if you want to visit the Frida Kahlo house]. And no visit would be complete without exploring a section of the Paseo de La Reforma - one of the grandest boulevards you'll ever see.

All of the above not an exhaustive list but based on favourites from my short time there.

Where to eat
Again budget will prevail and you're never far from some tasty tacos or chorizos sold by street vendors - and heartily recommended. A word of warning re what you drink though: fresh fruit juices might seem like a great idea at the time, but many of them are mixed with tap water, so your constitution may subsequently suffer.

For dinner my winner was the San Angel Inn, in the south of the city. From downtown it's a good 45-minute cab ride but well worth the effort. Set in a colonial hacienda you'll be treated to exceptional Mexican cuisine and serenaded [if that's your bag]. Cliched, I know, but ask for a Margherita here - mixed and served to perfection.

Well that's my three pennies-worth. Have a good [and safe] trip.