Staying with Luz was a superb experience. Her place is clean, cosy, tidy and comfortable. Everyone loves Luz, and you will too - she's exceptionally friendly and welcoming, and knows an incredible amount about things to see and do around Mexico City. Her place is within easy walking distance of the metro, which is a blessing, as it opens up the whole city to you, and puts you within easy reach of other transport hubs (bus, airport etc). There are plenty of local buses near Luz's place, as well as lots of cheap places to buy groceries and eat out.
On the whole, I can't recommend Luz and her place enough!