P.H.
I LOVE stations like we do on party day at my child development center,Creative Corner. Have several small tables where 4 kids at a time can work:
1.cupcake decorating with all kinds of sprinkles (then you don't have to have a big cake)
2.Playdough table with all kinds of rolling pins for playdough and cookie cutter things. Let each child take home a small can of playdough as part of the party favors.
3.Bubble table with all kinds of bubble wands and a huge tub of bubble mix..(get recipe online)
4.Moonwalk/bouncey
5.Large splash pool with dollar store toys to play with in the pool and water guns.
6.Table for water color painting and let child take home their painting or let them paint a muslin triangular shaped bandana...
7.Have a standing sandbox to play in that they don't have to sit in and get all sandy.
Party favors:
bubbles (6 pack from dollar store) squirt gun,bandana they painted and small pack of playdough or beachball from Dollar Store.
Don't forget to put the chldren's names on anything they work on prior to the party starting like the bandana, beachball,bubbles,
Make it a beach themed party and have the children arrive in swimsuits. Ask a couple of Moms to plan on helping you with certain stations.
Children this age have such short attention spans and need to keep moving before they get bored.
Good luck and have FUN!