Reading those right now! Never finished them all the way the first time, and now I've forgotten enough to read it all again. I was actually thinking about what it'd be like as a comic!
Hmm as for me... Dragon Bones/Blood by Patricia Briggs probably. It's pretty long but I really, really like the characters. Especially a certain ghost. I'd also say BBC's Sherlock, but that even has a legit comic in Japan already haha.
Gee I'm noticing now I haven't read much lately. I really need to get back into plowing through epics again, it's my lifeblood next to drawing.
Actually, I'd probably go for mythology and old epics, like Heike Monogatari or Norse Mythology. Excerpts at least, it'd be so tremendously long to make all of Heike into a comic. I didn't even get through the first chapter because I kept having to take notes on family trees n stuff xD (It's fun! For nerds. Like me. But it takes time.)