Oh, Moby Dick is boring, but it's also "wicked" because it's one of the finest examples of the character of early American literature. And, hey, it's filled with lots of wild homoerotic images that make for great discussion.
On a more serious note, I agree that it's particularly important to understand the cultural context in which the novel was written. Although Moby Dick doesn't fall into the category of colonial literature, it's shaped by the experiences of writers like William Bradford, Edward Taylor and Mary Rowlandson. Colonial literature is dominated by Puritan ideology, but confronting it is the mysterious, dark and very dangerous American wilderness. I mention Rowlandson (instead of Anne Bradstreet) because The Captive is a great example of how these two forces--the physical world of the wilderness and the spiritual world of Puritanism--intersect and interact. Remember, while the pilgrims suffered terrible religious persecution in England, a tremendous number suffered much worse (disease, starvation, hypothermia) in an effort to "colonize" (live on and off of) a land on which few human beings had ever stepped. The wilderness is other, alien, an unknown that scares the pants of the Puritans. They try to fight and conquer that fear with faith. The desire to control the unknown, civilize the uncivilized, is specific to American literature, American culture and American life.
I believe one reason Melville provides readers with so many details about whaling is because he wants to firmly plant his characters and his readers in a physical world, a horrible physical world at that (boy, whaling is such enjoyable, easy work, ain't it?). That world, I think, is contrasted with the spiritual world that guides Quequeg. And then Melville throws in this monstrous, mean-*** whale and Peg Leg, who's clearly missing a little more than just a limb. I prefer the idea that Ahab's missing leg, his obsession with his missing leg and with capturing the beast who bit it off, is a representation of a man who's lost his faith. If he can catch that whale, he can resolve his spirituality with his physicality and be a nice whole person again. I like that theme, but that's just one way to look at it. Of course, there's also the man versus nature theme too. A lot of critics also like the idea that Melville wanted to explore spiritual faith: if we can conquer the unknown, then we can be the masters of our universe as well as our fate, in which case some people, perhaps Melville, might question why we need God.
Did I just write all that. Sorry. Hey, on a lighter note, anyone ever read Louise Erdrich's Love Medicine? Contemporary American literature. Many of Erdrich's characters are Indian (Cherokee, I think), and in one scene an old Indian woman walks into her kitchen to find her grandson reading Moby Dick. When she asks what the novel is about, her grandson answers, " A while whale." The grandmother replies, "What do those whites have to wail about?"