There is not going to be a whole lot to see on the Crescent from DC to Atlanta. You traverse both North and South Carolina entirely at night, along with a chunk of Georgia and Virginia.
It should be daylight both leaving and returning DC and Atlanta. Between Lynchburg and DC is quite pretty and you will see it on your return, provided the train is on-time.
The North Carolina portion is quite industrial, mostly shuttered textile mills. You roll right through the middle of Greensboro and Charlotte, and will have a excellent view of each city's downtown. In a year or two, the wonderful Greensboro Southern Railway Depot will reopen after a long restoration. It will be quite nice - much better than the current facility in the freight yard.
There is about a half-hour scheduled stop in Charlotte, but the station is in the middle of the Norfolk Southern freight yard a couple of miles from downtown. The train rolls directly beside Bank of American stadium and Charlotte-Douglas International Airport.
I found the Crescent to be an excellent train. My dining car experience was excellent and the overall service was very good.