Here's a recommendation on how you can organize a 4-5 day trip to Mexico City. This will depend on what you wanna explore!

The best neighborhoods to stay are: Condesa, Roma, Juárez or Polanco. However, staying in Santa Fe just for the wedding is going to be easier.

You should use Uber/Didi to get around and drink bottled water only!

Bring a bit of cash just in case. $100 USD should be enough and you can exchange it at the airport upon arrival.

Tipping is usually 12-15%.