depends how much moey your have i'd suggest 10 days to 2 weeks first time and dont stay the whole time in the same place. It all depends on the style you like Ibiza is anything you wat it to be rom a very grown up restauranty /chill experience with art etc to wild juvanile lunacy. I like a thick well mixed portion of both, with some stunning scenery thrown in. Have no fears going on your own, collect a few numbers of here, tilllate and DSI (as if you'll need them) because youre neve alone for long in Ibiza it has the greatest atmosphere. I suugest staying in Playa Den Bossa (Bora Bora, Dalt Villa (restaurants), Pacha, Love, Space, & El Divino, Salines Beaches) as its close to all the best stuff, but you have to try San Antonio (Eden, Es Paradis, Cafe Del Mar, BarM) or another location just to see as much as you can and according to what you like. Bloody hell i should run tours!