I will be in Ibiza for July as well. The club season opens in June and closes in September -- so July will be fine. Don't go nuts trying to plan everything, however here are some nights that you just can't miss....
--- Big Nights Out ---
1. Sundays at Space -- if you have energy left over then the carry on party at DC-10 Monday morning
2. Wednesdays: Subliminal/Underwater at Pacha
3. Thursdays at Amnesia when Paul Van Dyk spins
4. Any club/any day when Danny Tenaglia spins
The other nights you can choose depending on your music preference.
If u're there on 13th July I'd definately check out Judgement Sunday on that night. It's in Eden, not the best, but Johan Gielen is definately worth the entry fee on his own plus u've got Haliwell (V.Good) and of course Jules (can be good occasionally )