Mike,
I can't think of a particular book, though Simon Nowell-Smith's "Edwardian Era" (Oxford University, 1964)is a good one, as it focuses not only on upper class life, but you're on the right track I'm sure as to the horse/buggy.
However there were taxis even then in large cities, at least. I remember reading that New York City had its first traffic-jam in 1910 so transportation was definitely even then getting past the horse/buggy stage. But heading out to some out-lying area must have been difficult in those days because roads were awful and cars were notorious for getting stuck. So a horse-drawn vehicle would have been the most reliable mode, I guess, in such cases.
There's a good chapter on early automobiles in the 1910-20 volume of the series "This Fabulous Century" (Time-Life Books, 1969)which has a great many pictures of average folk in their "tin-lizzies."
I don't think there's much about transportation in it but one of the best books on the simplicities and charm of life in the early 1900s - one I think everyone on this forum would be enriched by reading - is Jane Pettigrew's beautifully illustrated "An Edwardian Childhood" (Bulfinch Press/Little, Brown and Co, 1991). It is remarkable and will no doubt answer many other basic questions about life at the turn of the last century.
Regards,
Randy
