There are a lot of sunset photos over water and here is my sunset series. Most are from Sunset Beach, NC. In the fall and winter the sun sets perpendicular to the pier and the sunsets can be stunning.
As with most of my photography, my eye is drawn to reflections created by the light, sand and water. I typically start to shoot about a half hour before the sun dips below the horizon. I've noticed that most people stop taking photos soon after this happens. If you are one of these people, the next time stay for 20-25 minutes, particularly if there are clouds. This is the time that brilliant colors appear in the sky.