I've just reached 100%... yeah! I was at 99.5% because i missed a random character! Remember that you'll have to meet some of the characters several times, before they are "completed"! Also if you have used cheats during your game, it can block the 100%!! Otherwise I don't know what you are missing!! Maybe you could start all over
- it "only" took me about 50 hours to get from 0 to 100%.