My wife and I were watching a youtube channel and they spent a week in Mexico City. Even though they didn’t cover all the things to do there, it looked like a very interesting place.
Amazing city. Been lots of times. Highly recommend it. So much to see depending on what you are into. Food obviously is awesome. Real Mexican and not Tex-Mex Usually stay in Polanco or Condesa. Upscale parts of the city and reasonable prices. You can also travel out of the city to the pyramids etc. The old city is a bit full on and a bit of a tourist trap but good to see.
For around the city we used Uber and got a driver to go to the pyramids outside of the city for the day. Very reasonable prices. I think everyone goes to the Frida Kahlo museum also which was a bus from Chapultepec (when staying in Polanco).
I’ve been there several times, usually just traveling through but once I stayed for four days. I got around by bus and subway; it was very easy and inexpensive. I stayed in a cheap hotel just off the Zocalo.
One of the main reasons I wanted to visit the city was that in previous trips to Mexico I’d developed an interest in Mesoamerican cultures, and wanted to go to the National Anthropological Museum (National Museum of Anthropology (Mexico) - Wikipedia). I spent a full day there and could have easily returned for more.
Also, the ancient city of Teotihuacan is a bit outside the city, but well worth a full-day visit.