We usually stay at Marriott NW off the Windy Hill exit. So i'm not very familiar with many of the others. However, we have not received any complaints that I can remember from people who have stayed in the other hotels.
33'sdad, gives good advice. It's a good 20 minutes to half hour from the hotels to the East Cobb complex. Allow much more time unless early in the AM and especially from 3PM to 6 PM.
Early the traffic is bad going towards Atlanta and later the traffic is bad leaving Atlanta.
Anyway, that has been our experience. Lots of great eating places by the way. However, in our experience it's hard to find anything open after 10 or 11 PM. We spend about a month or more each year there.