Regarding
Citizen Kane:
It really does get better with repeat viewings. I also recommend listening to Roger Ebert's commentary on the DVD - it should prove enlightening.
As far as seeing more Hitchcock, I've got quite a few of his films on DVD so you'll have to check 'em out.
Frenzy,
The 39 Steps, and
Shadow of a Doubt are all top-notch.
It's a shame that there are still some excellent Hitch films still unaccounted for on DVD.