I think you have been given some great responses on here & I feel exactly the same way.
Kids will always be curious about things & they are never easy to explain. But evenutally they will be old enough to understand. Also as it's not the done thing any more there will be boys in the change room that are & are not circ'd, so there will always be the difference.
The way I see it, we are born that way & that's how we are meant to be. We don't go chopping bits of our little girls, so why do it to our boys. Needless to say my DH is Circ'd, but our DS is not.