You don't have to be 6' 4" like me to benefit from width in your swing. Regardless of your size, if you can maximize your width you'll create the most efficient swing possible. Here are my three keys for hitting it long and straight:
1. Create as much freedom as possible between your grip and your waist at address. If you create width like this at address, you can maintain it in your downswing.
2. Start your backswing with the clubhead moving first and let your arms and hands push back, away from the target. The important thing is that your swing feels big and slow.
3. At the top, your shoulders and trunk should feel fully turned, as if they can't go any farther. If you make a lazy shoulder turn, you'll lose the width you created at address.