Raw bars downtown?
A few you haven't mentioned:
Legal Seafood (K Street) - Kinda of a generic transplant of the never-as-good-as-the-ratings-suggested original in Boston.
Sea Catch (M Street in G-town) - Excellent restaurant with two bars, white marble up front and another beautiful wooden bar slightly further back.
Johnny Half Shells (P Street) - Not exactly a raw bar, but they stock most of the makings and offer some excellent prepared dishes as well.
Georgetown Seafood Grill (19th Street) - An outgrowth of the old Georgetown restaurant, it's a lot like the other standards, eg. McCormick's, Legal, etc.
Maine Avenue (Maine Avenue) - Not a raw bar, more of a market, and the quality is doubtful. But if you're looking for atmosphere....
If you're going to make a day of it, asked the Chowhounds for some recommendations in Annapolis by the city harbor. Riordon's?
In the old days, you were only supposed to eat oysters in the months with "r" in them (winter months). I think that was because of a lack of refrigeration back then, not because shellfish was out of season. Comments?
These days, the refrigeration problem is largely taken car of. Still, I like to stick to the more reputable places in summer, as you never know how long a bushel may have sat out on a pier, a loading dock, etc.
There were once two reasons to only eat oysters in the "R" months, and indeed one of those was the lack of refridgerated transport. The other reson boils down to sex. I wish I had my M. F. K. Fisher "Consider the Oyster" with me now, as she goes into fascinating detail about the sex life of oysters. In a nutshell, once the waters reach a certain temperature (usually late July to early August) the oysters gear up to shoot their love goo, which takes up a tremendous amount of energy. Their little bodies go flacid and milky - they don't taste bad per se, but they certainly don't taste great. Of course, now there are farmed oysters available from far and wide with different spawning times, and they farmers certainly aren't going to pull them out of the water before they spawn and lose future harvests! So, in July and August, it's always a better bet to eat only farmed oysters. Make sense?
FYI - if you eat them on the halfshell, avoid southern oysters - carry a nasty little bacteria.
Also Kinkead's at 20th and Penn, which offers on a 3-tiered platter their "Grand Shellfish Selection" (a version of plateau de fruits de mer) for $95. It consists of:
a 2-lb lobster
1/4 lb crabmeat
6 little neck clams
2 scallops ceviche
6 "jumbo" shrimp
12 oysters (usually 6 different kinds)
It is an appetizer for 3-4 people. It is served at every meal except weekend lunches.