Don't know if you looked at our Atlantic Coast Route but there's 2 maps that can give you routing. Atlantic Coast #2 shows routing from NYC to Conshohocken. Atlantic Coast #3 shows routing from DC to Richmond. Click on the following link, then click on the word Detail after numbers 2 and 3 which gives you a idea of where the route goes. The NYC routing doesn't start in the city - we recommend that you take a train to Summit, NJ, then begin riding from there.
You can also get in touch with the bicycle coordinators for the states in which you will be traveling through and need routing. Many have online resources as well as printed materials. Nearly every state publishes a bicycle map of some sort that they will send out for free and the coordinators often have more information they can distribute for no charge as well. And while the maps aren't as detailed as ours, they generally offer suggested roads for cycling through their state. Here is a link to the contact information for all of the bicycle coordinators:
For more tips and ideas on how to create your own route, see this blog post on the topic: