Arts and crafts
Arts and crafts are a winner because once you've set it all up, your kids can spend hours, days, even weeks working on a project while you put your feet up (just be careful about those scissors though).
Papier mâché's a classic - kids love getting their hands dirty. But also something as simple as some crayons, paint and paper can keep them happy for hours.
If you want to be a bit more creative, you could make jewellery, just be prepared to wear a glitter pasta necklace the next day.
Or you could try making a kite and trying to fly it, good luck!