All US-readers interested in crime ought to read the great four in american crime. Chandler, Hammett, John D. MacDonald and Ross MacDonald.
I agree, but your listing of both "MacDonalds" reminded me of a good "McDonald" author, Gregory. While not on the same level as the MacDonalds, his Fletch series is outstanding for those who are looking for something a bit less hard-boiled and contain some masterful dialogue. Don't judge the books by the Chevy Chase movies. They're good comedies (well, the first one at least), but the books are so much better and not as over-the-top.