Help! I'm being attacked by a plot bunny (it don't bite but the
cute widdle eyes are killer):

Shortly after Xander is Soldier guy he gets dragged to his mother's
family reunion - the Tackleberry family reunion (and gun show) - the
reunion's evening BBQ gets attacked by a group of vamps and demons -
Xander's the only one who knows how to kill them and make sure they
stay dead - the family now has legit targets and wants revenge for
the death of two of their own - The matriarch of the family
(Tackleberry's Grandmother) and Xander's dad, Xander is now importan...

Post season 5

Xander inherits a famous bar - any famous bar - and decides that since the gang is once again pushing him away from the slaying he's going to go run it himself.

How he inherited it is up to you - related to previous owner, Uncle Rory won it in a poker game, whatever you choose.

Spike is invited along as Xander would like some friendly company and well Spike is better than nothing.

Spike goes because the idea of being stuck without his snarking partner is a bad idea.

Spike has either never had or has gotten over the Buffy crush.
...