I would like to see Buffy and Faith put in a situation where they have absolutely no choice but to trust and depend on each other (like maybe a desert island with no grocery stores and no cable tv so they have to spend their time either searching for coconuts or fish, or actually talking and getting to know each other) so that they can finally become real friends. Just so Giles isn't left out, he and Andrew can team up to search for them.
Also, somehow, I would like to see some sort of team up with Faith and Illyria or Faith and Spike, or maybe all three. Just so Angel doesn't feel left out, he and Andrew can be locked up together in some sort of demon hell hole and the other three can be trying to rescue them.
And one where Kennedy and Andrew get turned into frogs and Willow has to team up with Oz to find them.