A New Zealand sauvignon blanc, and/or a nice chardonnay.

Outdoor party drinking does not favor nuance. In my opinion, a good red wine would be a waste in that situation. NZ sauvignon blancs are fruity and refreshing. An oaky chardonnay can stand up to plastic cups, chlorine smell, and whatever else would otherwise detract from a wine tasting experience.

Those are lame choices for a dinner party, of course, but might be perfect for a pool party.