There was a streaming series based on The Man In The High Castle, but I'm...for some reason, not really a big fan of that book.
A Scanner Darkly was interestingly faithful and slightly different from the book. Most of the plot was still there but the degree of Linklater humor worked in was of interest, I kept my DVD of that one and really like it.
I really would like a Ubik movie and am not really sure why one has never happened yet. Have you read that one? For now, that's my pick for his best book, at least of the nine I read.