Uh, no. You've got that pretty wrong. There's several different sides to Ibiza. People commenting above focussed on San Antonio, because that's where you said you're staying.
In San An, the wildest, cheapest, craziest bars and nightclubs are in the West End. That's where you'll often find uber-drunk guys and girls whooping it up.
The nicer restaurants and bars are, for the most part, in other parts of San Antonio (sunset strip area, further north, back along the bay).
Two of the islands super-clubs are in San Antonio (Eden and Es Paradis). The other big clubs (Amnesia, Privelege, Pasha, El Divino, Space, Penelope) are elsewhere but you can get to them by public transport.
People in the big clubs range from 18 to 60, so I wouldn't say they're for any one age group. People usually go to the big clubs to dance all night and have a good time. I've never viewed them as much of a scene for "chatting up". Nor have I ever really considered them "hyper".
The other main resort areas of the island - Ibiza Town, Playa d'en Bossa, Santa Eularia, etc. - all have different vibes. Santa Eularia is relaxed and older, with some great restaurants and a nice boardwalk. Ibiza Town is more cosmopolitan with lots of great bars down in the harbor and restaurants in the Dalt Vila (old town section). Playa d'en Bossa, home of Space and Bora Bora, is relatively young and international.
These are, of course, sweeping generalizations but DO take the time to get around and see more of the island.