I would seriously consider doing at least 5 days in Ibiza, and I would recommend that you come Sunday morning and leave Thursday afternoon...
Now are you ready? All the parties listed below are definately not to be missed!!
Start with Sunday at the Space, and IMO it is totally fine to get there early afternoon.
Monday morning - DC10
Monday evening - Cocoon @ Amnesia
Tuesday morning - manumission carry-on @ Space
Tuesday evening - go to Underground/KM5 for a more relaxed night
Wednesday evening - La Troya @ Space
Thursday morning - La Troya carry on @ Space.
I know it seems like you wont be seeing many of the other clubs, but these are by far the best parties in Ibiza. BY FAR.