Good front speakers create a good "stage" placement, the centre speaker is actually for those people who are not within aprox 30 degrees in front of the screen. (because the are not in the "sweet spot"). So if you are right in front, no center speaker has to be used. In my opinion it even sounds better with center switched off.
So if you watch with one or two people the problem is solved.
But if i had to choose for the position, just below the screen (i use a part of the mirage omnipolar LCR combined with infinty SW10 subwoofer as a center)