Of course you make no big mistake if you book the Holiday Inn Atlanta Airport (without south), but you'll have to drive a mile. Next to the conference location, there are at least 3 hotels next door and 20 hotels within a mile.
PS: Seems like the Sleep Inn Atlanta costs less than half compared to the Holiday Inn Atlanta Airport South and it's just a 300 ft walk.
For the REAL Studio Conference 2011 in Essen, Germany, it's a bit trickier. The Unperfekthaus is nice location for events and I really like the room 154 for our conference. But even if they have a hotel part, that is more like an holiday apartment (7 rooms) and too expensive for a normal visit. The best choices may be the Holiday Inn Hotel in Essen, just 350 m away from the Unperfekthaus and my favorite. Hotel Lindenhof may also be a choice and is even closer to the conference location. Finding a hotel is in general not too difficult as as I know there are not other big events which would make hotels a difficult task.
See you there!