I learned to speak Latin American Spanish; but my boyfriend learned the Castellano variety of Spanish (via 12 weeks in Malaga, Spain). When he practices his Spanish with me, I can't understand a word he says! Then again, my boyfriend is British so that English accent of his kinda mucks things up.
At any rate, I've never been to Spain myself; however I understand that Ibiza can be pretty crazy. The coast of Spain is a very popular summer holiday destination for Europeans and thus it can get crowded and "goofy". You'll be there early enough, so you'll probably get to enjoy the coast and nightlife without some of the problems.
.....Kelly