Re: Currents in the C&D Canal
Skip Smith Island and Tangier. You can take a ferry to either island from the shore for a day excursion. Tangier is nice, quaint and underwhelming. There are submerged hazards in the area and it puts you in an undesirable part of the Bay for fast North-South travel. I would stick to the Western shore in that part of the Bay and jump from the Great Wicomico (or parts south) to Solomons Island (or parts north) or vice versa. Fleet Bay has some beautiful anchorages as well.
There is such a long stretch without good anchorages North from Solomons (except Little Choptank) and a long day's sail from Great Wicomico to the mouth of the Bay, where you can anchor at Cape Charles or Kiptopeake for the Northern Channel, that I would not stop anywhere in the vicinity of the mouth of the Potomac. I love the area for daysailing, but it is less than ideal for anything other than leisurely local cruising or travel.