Wow. Ok, lucwarm, I work about across the street from the Mariott Marquis. If you drive in, make sure you know ahead of time where you’ll be parking.
My other suggestion, if you don’t need your car downtown is to go someplace close to the Marta lines. Near my house (and I’m close to the N. Springs, Sandy Springs, and Dunwoody stations…Perimeter Mall area) there are several hotels - some of them are listed here. It also lists some hotels in Marietta - those are a bit further out, in Cobb County. I’d stay away from Cobb and Gwinnett counties if I were you. Traffic can be horrid, or it can be decent. Just depends on how lucky you are.
If you’re flying in, you might check the airport area. There are a lot of hotels down that way as well. If you choose to take MARTA into town, you need the Peachtree Center Station and go up into the Peachtree Center food court area, then take the catwalk thingies to the hotel.