Illuminatus! Trilogy by Robert Shea and Robert Anton Wilson. I read it like 8 times in the two years after graduating college. Haven't read it recently but its a brilliant novel. There must be 150 charecters with about 12 interweaving plotlines including lots of sex, drugs, international intrigue, revisionist history, conspiracy theory, smugglers in golden submarines (well, only one really) and talking dolphins.
The whole trilogy is published in one volume about 1400 pages long and the first time I read it all the way through I cleared it in about 4 days; the first book is very fast paced and jumps all over the place so you have to promise yourself that you'll read at least 100 pages in the first sitting and not worry about comprehending anything - cause you won't.