couple of other suggestions - check the PH level of your lawn, most in the mid-atlantic need lime. Also, till/aerate the lawn before putting down seed. And as others have said - watering is key. Most laws in this area will struggle without an in-ground sprinkler system. Oh, and don't bag your clippings.
FWIW, We've had really good luck with Biogreen as our lawn service, when they took it over the lawn was a mess. The first thing they did was tilled the dead spots and then apply seed. We're paying about $350 a year for their service. If I were to buy Scotts and apply it myself, plus spot-kill weeds, it would cost me about $250 (we have about a 1/3rd of an acre.