Twelve Centennial Park.
It's downtown, affordable (for Atlanta -- weekend rates start at $149), has INCREDIBLE views, a full-kitchen, balcony off the bedroom, HUGE modern bathroom, flat screen TV's, computer with full Internet access, a restaurant in the hotel, parking, there's also a taxi stand right out the back door of the hotel. It's within a few blocks of the Aquarium, the Coca-Cola museum, and other touristy things.
It's also on the MARTA line -- you can take a MARTA train straight from the airport to the hotel.
I love this hotel.