I’ve read analyses that suggest US presidents should have an IQ of near 120: high enough to be intelligent, but not so bright as to be odd, or excessively disconnected from their fellow citizens. From this article on creativity, it doesn’t sound like there’s a lot to be gained in the creativity department once that number is reached.

This is like a lot of things regarding human nature and human development: there’s a minimum threshold (a moderately stimulating environment for a newborn, as an example), but there’s not a lot to be gained by going over that threshold.