The city itself was fine – bit touristy and with a real faded glory but a few great places to eat and drink in the city itself, can send some if you think you’ll go. It’s also really hot and humid. We mostly used it as a base for daytrips out to places like Uxmal and Celestun which were brilliant. It’s also surrounded by Cenotes which I’m sure you’ll have tons of in Tulum but they are so so much fun.
I’ll send some Mexico City recommendations when I get a mo.