My wife and I are both PMs, and living in ATL we use the CRCs here regularly before departure, and both think A Centerpoint is the best CRC here (it's not open on weekends). Other really good options include the one on the International Concourse (E) that is a straight CRC (not the BE lounge) and the one on Concourse T is very nice as well.

The one on Concourse E has showers.........but you have to bring your own towel. (just kidding--I think )

Concourse E also has better food selections/shops if that is important to you.

B25 is bigger than B10, but I'd avoid both with that much time to kill.