I don't know if you also want to include historical dramas in this, but if you do, I am rather surprised that nobody has mentioned "Upstairs, Downstairs". It deals with class differences and does it well.
This series is of course British. However, "Homefront" (1991-1993) is American and was also done exceedingly well. This show deals with life after WWII and has upper-class characters as well as working-class characters, but considerably more of the later, I think.
The third I wanted to mention is the Danish "Matador." Deals with life from the early twenties to the late forties in Denmark. An excellent, captivating series with plenty of working-class people. In all these shows the differences between the classes and the plight of the poor and powerless is also explored thoroughly.
Again, not sure if this is what you were looking for but as these shows are ones that I loved and that made a strong enough impression on me that I remember them in detail all these years later I thought I'd mention them :)