My faves (including stuff you already have, just for completeness):
V For Vendetta
League of Extraordinary Gentlemen (Vol 1 and 2)
Watchmen
Top 10
Kingdom Come
Planetary: All Over the World
Planetary: the Forth Man
The Authority (The first two Collections, after that it went downhill)
Sandman
JLA (The most recent series, up through around issue 50, i.e. up through the World War III storyline)
Ex Machina
Stormwatch (The last 2 or 3 collections)
Dark Knight Strikes Again
I cannot say enough about Watchmen and V for Vendetta. Have to be my favorite graphic novels of all time.
And I still haven't read Maus, which makes me sad. I really need to read that.