Tilt up when you want to move the runner over or home with a sacrifice fly. Tilt the box down to hit grounders behind advancing runners. Don't always tilt the box to its extremes. Use every angle available. The power swing is most effective when using a power hitter.
Weaker hitters are usually more effective when using the contact swing.
A strong power hitter can not only park the ball with a power swing, sometimes a contact swing angled just right can clear the fence. Guessing both the type and location of a pitch will result in your batter having an increase in his power for that swing. If your player has a blue zone, it's a good bet that the opposing pitcher will try and take advantage of it. Guessing both pitch and location on the same at bat is a risky proposition. Smart batters usually only guess when ahead in the count and hardly ever when behind.