there r other alternatives, but they r inferior to what u urself submitted: the fast crowd (not necessarily young, but usually that's implied); the in-crowd (not necessarily rich and young, but being either or both help to get membership); the rich and the beautiful (again, not necessarily young, but in our increasingly youth obsessed ageist cultute beauty often equals youth); or the brat pack (rich, spoilt, unruly kids). u pick

Like Tara something Palmerson, Tara Reid, Nicki Hilton, etc. If they start doing something, like singing or acting, they become singers or starlets/actressed, no longer It girls. (and boys)