I'm not a big Western fan, they tend to be too conservative for a big liberal like me. The strong, silent good guy is the best shot, so he kills the bad guy, saves civilization and marries the schoolmarm (My Darling Clementine, Gunsmoke). I tend to prefer the "adult" Westerns of the 50s like Man of the West, The Unforgiven, 3:10 To Yuma, Johnny Guitar and Warlock that acknowledge that there was sex, racial tension and moral ambiguity on the lonesome prairie. Another interesting variation was Western family drama, like Broken Lance, Duel in the Sun, or Giant, where a powerful paterfamilias was respected throughout the county but had trouble with his own family (Bonanza is a watered-down version).
The Big Valley is the closest TV came to the adult Western. Of course it was constrained by censorship compared to the movies, but it was daring at the time to have a main character be an illegitimate son of late paterfamilias who is accepted by the family as one of their own (after some conflict, of course). Also, the prostitutes were actually whores, not the fresh-scrubbed "dance hall hostesses" of Bonanza.
Unlike the usual powerful ranching families in movies and TV, the Barkleys were headed by the strong-willed Victoria as played by the great Barbara Stanwyck, who after the first few episodes took to wearing an all-black cowgirl-dominatrix outfit reminiscent of Joan Crawford in Johnny Guitar. Instead of ruling the valley with an iron fist and fearing change, the Barkleys were the 19th-century equivalent of "limousine liberals", always helping the less fortunate, whether they are poor farmers, black ex-cons, prostitutes, Mexican revolutionaries or inmates of a women's prison (Victoria goes undercover and endures beatings in order to expose its inhumane conditions). Unlike the many movie Western heroes who are embittered ex-Confederate soldiers, like John Wayne in The Searchers and the many versions of Jesse James, son Jarrod was the captain of a black Union regiment. Still, they are often resented and even kidnapped due to their wealth. Poor Audra, the daughter of the family, was always being threatened with rape, most memorably by a psychopathic Civil War vet played by Adam West.
The Big Valley has something for everything with its three brothers: smart, sophisticated lawyer Jarrod; hot-headed diamond-in-the-rough Nick; and quiet, brooding friend-of-the-underdog Heath (Lee Major looks and sounds a great deal like Elvis Presley at this point, which I assume was intentional). Not to mention the uncannily lovely Audra and the intriguingly butch Victoria. There are many great guest stars: having only seen the first DVD of the first season, I've already enjoyed Andrew Duggan as a charismatic-but-warped Civil War general who tries to get the ranch hands to turn to crime, and Jeanne Cooper as the murderous Lady MacBeth of a dying Gold Rush town.
My other favorite TV Westerns, The High Chaparral and Maverick, are sadly not on DVD, but the 10 discs of The Big Valley, Season 1 should get me through summer reality-show hell.