La Condesa and Roma Norte and Roma Sur need very little by way of description. Long the most-visited by international guests, they're some of the neighborhoods that have historically welcomed visitors from all over the world and continue to do so.
The Roma - Condesa area is generally divided north-south by Avenida Insurgentes, with only a part of Roma Norte to the west of Insurgentes. Most of Roma is to the east.
In fact, La Condesa is generally lumped in with three more neighborhoods on their side of Insurgentes: Hipódromo 1 & 2, and Hipódromo-Condesa. These four parts of Condesa and the horse-track layout of the streets are pretty much the epicenter of international visitation to Mexico City.
Condesa makes a nice transition-staging area for guests who are truly in culture shock or who need a familiar terrain to adjust to altitude sickness.
They're also a place to experience some of the heights of Mexico City gourmet cuisine, peaceable grown-up nightlife, and a good smattering of boutique shops and galleries.
Roma (North and South) have not changed terrifically from the residential calm depicted in the 2018 Alfonso Cuarón film, even though that film is set in 1970. That should tell you something about the neighborhood.
Lots of residential architecture here is happily mid-century, and residents are not anxious to modernize.
The epicenter of "Hipster" culture, it's even more of an epicenter of daring cooking, daring nightlife, and bit more experimental gallery and music scenes.
Always rougher at the edges, Roma has charm, too, sometimes by the bushel. And as a place to stay, it's often second-choice after La Condesa, but many visitors will see, it's the place to be, morning, afternoon, and night times, too.
Below are just the beginnings of the places to be exploring, and there are a lot of them.