R.R.
My oldest's birthday is the end of June so I know what you mean w/ trying to plan something for everyone. She is a bit young yet but for sure as she gets older do the water party idea I did it one year for our son and it worked Great so we did that for a couple yrs (till we moved away from most all our family and friends due to DH work). I put out the kiddie pool and we got a slip and slide one yr, we bought some cheap water guns (those were also the only guns our boys were allowed to play w/). It worked really well, the kids hit the slip and slide and several of the adults gravitated towards the kiddie pool where the water guns were floating. Everybody just had a Ball!!! GOOD LUCK!!