I don't get why you don't want to be clipped in while you're accelerating through traffic. That's when being clipped in seems to help me the most...

I've noticed that if you wait with your 'foot off' side in the down position, you should make sure the part of the pedal you want your foot to land on is facing the ground. In your case, the platform side. When the crank moves to the up position when taking off, your foot should land on the platform side. I've reached the point where I check every time I stop to make sure my cleat side is facing the ground so i'll clip in automatically and it seems to work usually.

Although, I agree about the powergrips.. maybe better for you.