The MARTA is really hit-or-miss IME. It’s relatively easy to get back and forth between a handful of places, but last mile is spotty and you may have to walk a ways, providing you even can.
Chicago has a good public transit system, for most places in the city. That works out for me, because I do not want to park in the city and I don’t really even want to drive to the city. However, there’s no decent public transit in the burbs past Cicero* or so.
DC is supposed to have a great public transit system, but I think it’s overrated. Too expensive, and not nearly as convenient as the locals say it is.
*and then you’d have to live in Cicero, which I do not recommend.
