November is late, but they import the crabs from Louisiana (don't worry, they're still blue crabs and steamed and seasoned correctly). You'll pay more, but that's OK. Also, spring for the larger crabs; otherwise you spend forever picking and not enough eating.

If you've never had them, don't wear any clothes with long or wide sleeves. For that matter, don't wear anything you like that can't be washed- crabs are MESSY.

Both places are nice restaraunt, not traditional crab shacks (which are high on value but low in ambience) so I don't know if they do the crab feast traditional style. This is how it usually goes:
You order the crabs by the dozen or bushell (that a lot of crabs).
The waiter comes out, clears the table, and lays brown paper on it.
You get a mallet (for cracking claws ONLY!) and a knife (for which I have yet to figured the use) and a couple of rolls of paper towels.
Take some paper towels off the roll before the crabs come out!
The crabs are dumped in the middle of the table and the feast begins.
Let a native or waiter show you the proper way to pick the crabs. It isn't easy to explain.
You'll need to make sure your drinks are full at all times- crab feasts are thirsty work.

Plan to spend a lot of time at the restaraunt!

Enjoy Baltimore.