Jon, I'm going to jump on the bandwagon, Watchmen is the greatest graphic novel ever written, and you seem to have missed a fair bit of it.
Personally the thing that does it for me with Watchmen is the incredible scope of it. There is SO MUCH GOING ON in that book, and it is all integrated into a seamless whole. I'm pretty sure I still haven't exhausted the levels on which the book can be understood, and I already think it's the most successfully complex and multifaceted graphic novel in history. There are simply no chinks in the universe. Any one of the stories in it (Rorschach's story, Dr. Manhattan's story, Ozymandias's story, The Comedian's story, Nite Owl's story, Silk Spectre's story, etc., etc., etc.) could be a successful stand-alone work, even the minor characters like the libertarian news editor or the lesbian couple or the psychologist are exceptionally developed, but Moore has managed to put them ALL into a single work without losing the power of any of them or sacrificing the story to the characters. I don't think any of it could be taken out and I don't think anything could be added.
Anyway, I just read Warren Ellis's "Black Summer," and it's awesome.