The Wilderness Tarpon 130 T double sit on kayak is a great example of the fine sit on tops that Wilderness Systems make. A really well finished double sit-on that will suit 2 adult paddlers or 3 smaller paddlers. The 130T has flip up back rests that offer really good supprt to the lower back. A fine v shape to the bow makes for a smooth and easy touring double, although fun in small waves this double won't take thigh straps so is not suitable for larger waves as control is reduced.
For more surf fun check out the Perception Gemini.