I recommend that you read Mark Twain's "Roughing It." Twain had an excellent ear for dialects, and he went a long way toward capturing the everyday speech of the West. The bits of slang that worked its way into the regional dialect often includes a lot of words from Spanish - words that are more common in the larger vocabulary today but at the time sounded strange - arroyo, canyon, ranch - were all strange sounding to the "States" as the early West referred to the East.

In addition - one of the reasons I couldn't watch more than a few minutes of "Deadwood" was because they got the language so very wrong. The West was known for its foul language, but in the context of the time and place, that meant that they blasphemed a lot. They didn't use vulgarities in everyday conversation in the way that the program depicted. There is a dividing line that separates taking the name of God in vain (and saying "damn!!!!") and talking about sucking cocks. The former was daring and common; the latter was too vulgar to be acceptable even in most conversations.

And they said "you bet" a lot. You bet they did.