There are three social classes in America: upper middle class, middle class and lower middle class. Miss Manners has never heard of an American's owning up to being in any other class.
-- Judith Martin, Miss Manners' Guide to Excruciatingly Correct Behavior
As usual, Miss Manners manages to condense my perceived reality into a couple of crystal-clear sentences.* I, too, have never heard anyone describe themselves as anything other than middle-class (possibly because Americans think of this country as a meritocracy), though we will occasionally talk about our "blue collar" forebears in oddly romanticized language. Those TV folk in particular speak as if they are addressing a country made up entirely of middle-class families.
This is completely at odds with reality; the truth is that our country is incredibly classist. The economic disparity between the rich and the poor in this country is more pronounced in the U.S. than it is for our international peers. Sociological Images has some great summaries of how we stack up internationally, and of how the gap between our rich and poor is growing rather than shrinking. If you move beyond simple economic classes, you find additional discrimination based on race, religion, gender expression, and sexuality.
I'm not quite sure, though, what language would be preferable. I hesitate to describe myself as "upper class" because I'm afraid of sounding like I think that's some sort of compliment, rather than an honest assessment of my economic privileges. (On the other hand, it also brings to mind debutantes and weekends in Martha's Vineyard, and it would be useful to stop equating wealth with these practices.) But we do need a better way of discussing class, because thinking of this country as filled with middle-class people sweeps real economic disparities under the rug.
And yeah, my references are all from Sociological Images. That is an amazing site, y'all.
*Then again, Martin and I seem to have led similarly privileged lives.