An alibi would be nice - so would a quick getaway for everyone. And it would be good to see a little of Lois as a Slayer when she gets back to Metropolis; it's not that far from Cleveland, which will be the main US Hellmouth with Sunnydale gone, so there ought to be some supernatural activity. Lois is about the most mature Slayer, so I can see her being asked to take charge of any others assigned to Metropolis.
Where Clark goes from here is also interesting - he won't be happy about what he was made to do, maybe he'll want Willow to strengthen his magical defences, or once he goes into business as Superman, ask her to help with cases involving magic etc. e.g. the voodoo story.
Belated thought - if Clark is vulnerable to magic, so are the New Kryptonians. Consequences might be interesting...
