I lived in Atlanta for years and still visit family there. I think I may have some ideas, but I would like a bit more information about your layover first.
Are you planning on staying near the airport area or going more toward Atlanta itself? What kind of food are you looking for? As for hotels, well... I would highly recommend that you go with a reputable hotelier. I don't think I would want to stay in any of the lower cost places especially by the airport. It is a very transient area.
There are some great hole in the wall places as well as some more upscale places that may suit your fancy depending on where you choose to stay.
Whenever we have an overnight layover, which happens fairly frequently, we use Priceline and bid on a three star hotel by the airport. That way they almost always have a shuttle, a bar and a restaurant. The amount we pay varies from city to city, and what night of the week it is. But, it's usually less than 50% of the rack rate. Sometimes quite a bit less.
We will only have about 12 hours by the time we clear customs and need to return for he departing flight. Priceline sounds like a decent idea. All in all I'd say we don't want to get much further than 15 minutes from the airport via taxi or shuttle. Normally KLCMAN has some ideas......You around my friend?
Bear in mind that you will have to re check luggage, and most likely* will not be allowed to do that until the following morning, so pick one bag for overnight and most importantly leave room for repacking you duty free liquids!
*Airline reps are often in the baggage area imeadiatley after immigration, are sometimes willing to help with rechecking, especially if you have an early morning flight, and are adept at looking pitiful
It's rarely rocket science, it's usually just math: then again if you can't do the math.......