If you're looking for a meeting place or a good stop around ½ or halfway between Decatur, GA and Elkridge, you can try Greensboro, NC, which is almost 5 hours northeast of Decatur, GA, or about 5½ hours southwest of Elkridge.
Other possible places to stop near the midpoint include Burlington, Chapel Hill, and Durham.
About ¼ or a fourth of the way, you can stop at Spartanburg, SC. This is about 2½ hours northeast of Decatur, GA.
About ⅓ or a third of the way, you can stop at Charlotte, NC. This is about 3½ hours northeast of Decatur, GA.
About ⅔ or two thirds of the way, you can stop at Opie, VA. This is almost 7 hours northeast of Decatur, GA, or about 3½ hours southwest of Elkridge.
About ¾ or three fourths of the way, you can stop at Richmond, VA. This is almost 8 hours northeast of Decatur, GA, or about 2½ hours south of Elkridge.
If you drive straight through without stopping at all, the total distance is 672 miles. The distances shown above don't include local roads to get into each town, so if you're planning a long road trip, make sure you factor in traffic and road conditions, rest stop breaks, and interesting detours along the way. If you're in a rush, you can do the trip with zero stops, and your total travel time would be around 10 hours, 11 minutes.