Michael - I posted a link to that list about six weeks ago in a link on the Astor family.
As David said - this is a pretty extensive topic and you'll really have to do your own research. There are certainly books on the history of New York high society and I'm sure that goes ditto for the other cities.
Then there are biographies of individuals. Suggest you start with reading about the likes of Winston Churchill (I read and enjoyed "The Letters of Winston and Clementine Churchill" this summer), Teddy Roosevelt, Alice Roosevelth Longworth, Vida Sackville-West, Alice Keppel, and most of the famous American and British writers of the time. Edith Wharton, for example, came from a distinguished NY family and married into a distinguished New England family. Virginia Woolf, Somerset Maugham, Henry James, Mark Twain and Evelyn Waugh, just to name a few, all mixed with elite people.
As far as the families David mentioned, the Astors were certainly creme de la creme in NYC by 1912 but they hadn't always been. Their position was attained through time, work and intermarriage with older families like the Rhinelanders.
J. Clinch Smith is on Mrs. Astor's list.
The Thayer roots are hard to trace but they are generally depicted as being of old New England stock. Some have claimed that the Wideners, on the other hand, were considered rather nouveau. In the book "Last Dinner on the Titanic", Rick Archbold and Dana McCauley make the claim that George Wideners father had started as a butcher before going into business with Eleanor's father, and thus the Wideners weren't considered among Philadephia's most elite.
But the Wideners certainly seemed to mix with the Thayers and Carters on the Titanic. Money talks.
From what I've read, I would say that the Ryerson roots are a mixture of older and newer stock. I THINK I've posted links to parts of their family tree on threads about their family.
The
Countess of Rothes was certainly typical of the English landed class. The Duff Gordons were not -
Lady Duff Gordon being a divorcee, in business and lacking an aristocratic lineage. Tyrell Cavendish was typical of an English aristocrat in terms of his background and birth, but not typical in that he was married to a Jewish American (though, of course, plenty of aristocrats did marry rich yanks).
Thomas and Edith Pears are an example of Britain's rich middle class.
There were plenty of American
first class passengers who had colonial roots and thus highly ideal family trees, but were not as well-known as richer families like the Astors and Wideners. Among this group, Helen Candee (as we know from Randy Bryan Bigham's excellent account), Edith Evans, William T. Sloper, Alice Silvey and numerous others come to mind.
Here I go writing a thesis again. That's enough out of me!
Regards