From the same director who brought us Citizen Kane comes another kind of cinematic hero (of sorts). Michael O'Hara, like the deeply flawed Kane, is flawlessly played by his creator Orson Welles. Unlike Citizen Kane however, this film fell under its producer Harry Cohn's butchery with considerable footage lost and destroyed forever. Nevertheless, what survives is vastly entertaining and not to be missed. (More here including Saturday morning's showtime information throughout the U.S.):
Even at 88 minutes this is still kind of a slog, but it's not the total mess the host claims it to be. Still, the ending is still a little bit of 'Wait, What?'.
For pure noir goodness you want 'Touch of Evil'. Welles's 2nd best movie, quite a nasty piece of work that is, and one of my favorite movies.
I like your description as Touch of Evil being a 'nasty piece of work'.. It is spot on. Its a hard film to like and bring yourself back to (a bit like The Big Combo) and I don't think I have since going to the cinema about ten yrs ago to see a restored version. The scene where Janet Leigh is violated, and it is left to your imagination as to what is going on, particularly stands out.