Okay....The Buffy-Expert coming through.
Okay; Spike would not work as a main character. He is an antagonist. In Angel Season Five, he was in his best role. It was exactly the same role as he was in in Buffy Season Four. In the Faith Spin-Off pitch, Faith was the main character with Spike, walking the Earth. Spike couldn't be the main character. We've already had one show about a Vampire with a Soul (to which my friend replied "yeah, Buffy").
About The Giles Spin-Off. Anthony Steward Head loves the Rupert Giles character, but disagreements between the US and BBC. But ASH has said that he would love to return to the character, even as a two hour movie or mini-series (think Silent Witness). But the series seems to be out of the question. And for your information; it was called Ripper. :-) It wasn't planned to be about the Council. It would've been ghost stories and the like.
Illyria...hmm...okay, false. How would it be about though? Redemption? Done that. Unless it could've been based on the Faith style pitch of a fugitive walking the Earth...I dunno, I can't see Illyria as a main character.
Connor...I don't know. I think that the biggest question will be about what a new series would be. They don't want to rehash the same premise as Angel and Buffy...but you don't know whether they will make any more. Perhaps they should make some brand new and fresh characters altogether and start from scratch if they really want to do that.