Congrats and good wishes on your voyage, I envy you! I plan on doing such a trip myself, but I have to wait 8 to 10 years for retirement in order to find the time.
Why did you guys wait till the worst possible time as far as weather is concerned to make such a trip? My plans would be to start out from Indiana, where I live, in late April and try to finish by early to mid October. The trip will be long, taking the northern route west to Washington, then down to California and east across the southern route to Florida then go north along the Atlantic seaboard up to Maine then head back west along the Northern route back to Indiana. I know that Adventure Cycling has maps showing these routes, so I'll follow those maps.