h2g2 The Hitchhiker's Guide to the Galaxy: Earth Edition

I know that I'm joining this one awfully late, but there are a few things:

You're right about the line of Slayers - it's on the death of an 'active' Slayer that the next one is called. That is what is meant to restore the balance to it all. Of course, they go and ruin that idea at the end of Season 7...

Hellmouths aren't that common. There are very few in the continental US (I know of two - Sunnydale and Cleveland). Cleveland is actually on a Hellmouth (Giles at the end of Season 7 - the end of it all )

LA isn't on a Hellmouth, it's just a big city where demons feel at home. It's certainly got the right kind of squallid atmosphere in some parts... And I think that, for Angel, it was important because it's where he made the decision to help the fight against evil. Course the main reason was probably because it would be easier to shoot - but Friends is shot in LA too, so...

The confusion over the Hellmouth in Cleveland - according to 'Chosen' there is one - in 'The Wish' he says

"Yes, I'm aware that there's a great deal of demonic activity in Cleveland. (listens) It... Well, it happens, you know, that, that Sunnydale is on a Hellmouth"

But as that's where Buffy went to instead of Sunnydale, you have to assume that there was some power driving her there, but I would think that it was TPTB, rather than The Watchers' Council

I have a disturbing amount more that I could say here, but I think that I should just be quiet now and move on...