I can't speak for the other books, but as AH goes, Man in the High Castle isn't at the height of plausibility (I know, I haven't read it, but I know a bit about it). One Alternative History book that you might like (assuming you havent read it), especially since you've said you read actual history books, is "For Want of a Nail". It tells the story of the Confederation of North America and the United States of Mexico, the two North American States that arise out of the failed American Rebellion. The best part of it is that it is written as a university level textbook on the events as if they were the actual history. It reads like a history book from another Universe. It's my favourite book evar.
And if you've already read it, consider it advice to everyone else. Buy this book!
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Sounds good, I'll look it up.
(Germany nearly managed to distract the US in WW1 by inciting the Mexicans to attack Texas ...)