Amtrak Wilmington <-> New York takes 1:26-1:50 and costs $52-149

The $26 weekday way from Dover to N.Y using Dart, Septa, and NJ Transit

6:31am 301 Bus Dover Scarborough -> 7:31am Wilmington Train Station ($4.50)
7:43am R2 Wilmington -> 8:43 AM Phil 30th St Station -> 8:52 R7 -> 9:43 Trenton ($9.00)
9:45am [or 10:18, 10:45] Trenton -> 10:58am NY Penn ($12.50)

NY to Dover

3:01 PM NJTransit from NY Penn -> 4:16 PM Trenton
4:39 PM Trenton R7 -> 5:28 30th Street Philly -> 5:42 PM R2 -> 6:33 PM Wilmington
6:55 Wilmington 301 Bus -> 8:06 PM Dover Scarborough

Delaware to Washington