In Act III, scene 2 of "Macbeth," is Lady Macbeth enjoying her new position?

No, not really.Consider these lines: "Naught's had, all's spent,
Where our desire is got without content:
'Tis safer to be that which we destroy,
Than, by destruction, dwell in doubtful joy"Here she's saying, we got everything we wanted, but we're not happy.  They don't have a chance to enjoy everything they've gotten—it's all crumbling away. Despite that, though, she's holding on to her chosen path, nudging Macbeth to put on a happy face and charm the guests so that they can hold on to the position they've won by their brutal methods.