If there's an electrical socket available take a cd player in for dance? there are some nice discs available.
Children's party time
A king sized bed sheet makes an excellent canopy for play. Where unfamiliar with what to do, invite children to hold the outer edges and flap up & down for others to run in & out, under and over. Include a few ball-pool balls to the centre of the sheet to toss up and roll around.
Bean game, balloons & bats for children looking for less structured activities?