First is "Sins": I have no idea who it was written by and I don't know where I read it.
It has a kind of emotionless Xander who meets up with Spike, I think there was a plane involved.
Second: I don't remember the name but Xander meets up with Spike in Africa after getting a new eye. I remember Xander saying repeatedly that "he has travelled with a chipped Vampire before."
Thanx!