IBIZA "Grown Folks Style".    While it may not literally mean "party 'til you drop," it certainly lives up to that reputation as one of Europe's top nightlife destinations. With over 100 miles of coastline and around 50 beaches, the island offers a variety of restaurants, bars, and water sports, not to mention the legendary clubs. For a touch of culture, explore the old town, which has been recognized as a UNESCO World Heritage site.