A few years ago I did a White Clay ride from Middletown to St. Michaels, MD. We stayed overnight at the Best Western and rode back via a mostly different route. I thin Saint Michaels would be a nice place to use as a base for day rides. Everything was pretty much pancake flat. Maybe one day you could incorporate a ride on the Oxford-Bellevue ferry. We took that on the way down.
You might also try getting in touch with someone from the Potomac Pedalers for ideas:
http://www.potomacpedalers.org/default.asp