Read Paul Fussell on socioeconomic class. (Kate Fox in her book Watching the English also has some interesting UK-specific commentary on class.) Some of the best stuff out there (that I know of).

Both of them focus on cultural and lifestyle differences, though -- just as a word of warning if that's not what you're looking for.

Gladwell in Outliers also has some interesting things to say on the influence of an upper class background on the skill to forge social connections, specifically in regards to comparing the respective achievements of Robert Oppenheimer (upper class) and Christopher Langan (very high IQ, but lower/middle class).