My husband and I sometimes trade roles, but I never really enjoy it. He's a bit of a switch, though mostly dominant, so whenever I do top, it's fully for his benefit. But I always feel like I'm putting on this big act, like I'm pretending to be something--someone--I'm not. And because I'm so focused on giving an Oscar-worthy performance, I can never relax and enjoy our intimacy. Plus, seeing him helpless and in my control, does nothing to arouse me, it's actually a turn-off.
Like csr said, "I'm just not wired that way..."