I'm with Irulan. If they're there for the month, do what you normally would. Laundry, errands, whatever. For that length of time they should be self-maintaining.

DO NOT train them to expect that you will provide all the entertainment and all the cooking and cleaning, especially if you are both working througout. If they want maid and chef services, make them a reservation at the local hotel.

Maybe even give them an assignment to trade off cooking a couple nights a week, just don't do a reverse-MIL.