I live within about 20 minutes of the CSX W&A sub and there aren't even close to 70 trains a day over this piece of railroad. It's actually more along the lines of 30-40.
If you can't afford the house though, a decent alternative is one of my favorite pizza restaurants, New York Pizza Exchange on Paces Ferry Road. The restaurant sits alongside the CSX main and has an outside patio that is within 15 feet of the tracks. The nearby Paces Ferry crossing is a "quiet zone" now with the protection provided by gates and lights but, it is still a good spot to watch trains and enjoy a pretty darn good calzone!
There is a plaque hanging on the wall inside the restaurant honoring a CSX train crew who noticed a fire in the restaurant during the wee hours a number of years ago and contacted their dispatcher who called the fire department. Thanks to the crew, the restaurant was spared any significant damage and that particular train crew have free dining at this restaurant for the rest of their lives.
Curt