Guys, the smartest, most clever character is almost always that of the smartest, most clever player.
A smart player can deliberately play dumb if it amuses him (I sometime deliebrately blunder for the sake of comedy), but a dumb player can't play a smart PC.
That's why my low to average intelligence fighter often has better tactics to offer than the 20 Int wizard. And I won't apologize for that!
Mechanically, inteliigence represent academic knowledge for the most part, memory also. In the case of a wizard, he demonstrate an impressive ability to memorize a considerable amount of data and recall it readily even under pressure.
But logic, common sense, the tactical ability to think a few step ahead? You have it or you don't. Stop looking at your stat sheet.