I presume that you are using the ATA and the C&O into Washington.
There is a ferry possibility by taking the Cape Lookout cruise to Smith Island then to Crisfield.
There hasn't been ferry service in the Annapolis area for 50 years since the bridge opened -
Plus bikes are prohibited on the bridge.
The state has offered shuttle service off and on saying that it is a courtesy even though ISTEA requires multimodal access. Some years the state hasn't even done that and you have to use a taxi at about $40. It really sucks. If you are doing the ride before the Cape Lookout cruise starts up then you really have to find a way across the Chesapeake Bay Bridge.
Back to the cruises:
Daily afternoon service from Smith Island to Crisfield - -
Limited, seasonal service from Point Lookout to Smith Island.
Departure from Point Lookout State Park 10:30 AM Wed. thru Sun.
June 17 through September 3, 2006
Pre-season dates: May 27, 28; June 10, 11
Post-season dates: September 9, 10, 16, 17, 23, 24; October 7, 8, 14, 15, 2006
Also - it's tricky getting out of Washington heading east. Southeast DC ain't a place you want to hang around in. The Mount Vernon Trail on the Virginia side is really sweet - but you have to find a way across the Potomac River to Marshall Hall (where there is a county dock). I hitched across before or you can call nearby marinas and see if someone will give you a lift.
Otherwise - my advice is to take the Metro from L'Enfant Plaza (bikes permitted during off-peak hours) to the end of the line on Branch Avenue. From there use Old Branch Ave and Brandywine Road to Cedarville State Forest where there is camping. (Camping is hard to come by in this area.) Then it's a moderate day's ride to Cape Lookout and camping.
On the Eastern Shore there is camping right outside of Crisfield at Janes Island - even better camping at Pocomoke State Park - stay on the west side / not US 113. At Berlin you can head out to Assateague Island. The State Park is more of a carnival than the National Seashore - plus the latter has walk-in remote sites which are some of the best in the region.
Have a good ride - J
PS - Check out the WABA website