O'Hare and Midway are about the same distance away, it will just depend on your preferred airline.
There is valet at The Drake and we will have a rate associated with the room block
I added a website that describes the dress code here: https://www.theknot.com/content/what-to-wear-formal-black-tie-optional-black-tie-invited
While we love your kiddos, this is an adult-only event with the exception of the children who are in of the wedding party.