Block Hotels and suites are very affordable and comfortable. They look like little studios. The room is really small but comfortable. It is really close to the main commercial district area (the Reforma, the Angel). It's easy to get to some of the main tourist attractions like chapultapec, and the angel statue. We booked some tours that picked us up at a different hotel near by so it was was really easy. Also - free breakfast.
Only downsides - the hot tub and fitness area are too small and really don't make sense. The bed mattress we had was ROCK hard. Much to firm for me.