I agree with the 'don't create more work for you' thing. I've actually labelled all houseguests into several categories:
- positive influence (ie have a positive helpful effect)
- neutral influence (any help is cancelled out by the work they create)
- negative influence (create more work than they are worth)
I've told hubby that during periods of anticipated stress (new bub, back to work, busy at work etc) only positive guests are allowed to stay.