Having exterior lights on motion sensors is great for a number of reasons, including safety and energy efficiency. Unfortunately, most exterior lights with built-in motion sensors are ugly. A solution to this problem is to buy a motion sensor unit (without the light) and install it yourself in some discrete location near the light. If the walls/ceiling are open this is obviously easy; if they are closed up you will need to snake wires. It's a little more complicated than installing switches so you might need to call an electrician.
Two earlier electrical posts:
In praise of push buttons -- electrical, part 1
In praise of dimmers -- electrical, part 2
FYI: The porch ceiling is made of 5" x 10 ft lengths of pine beadboard that had three coats of exterior-grade spar urethane applied before being nailed up.