Koontz is great, I love his stuff. the good guy is an awesome story, I won't ruin it for you by saying anything...
I know a lot of Kings books tie into the DT series(I have finished them), it's just I've read almost all of his books except pet sematary(was that how it was spelt? it wasn't cemetery,I think...), Carrie, and the first one with the vampires in it. oh, and bag of bones. and of course, the stand, which is why I wanted to read it before the DT series, but I got too into the DT. oh well, at least I understand a bit more about who Flagg actually is, then thinking he's like Satan or something....