Sea kayaks are the long-distance cruisers of kayaks. They’re designed long for easy tracking, and have capacious hulls for multiple days of gear. They’re not real fast or maneuverable, but they can get you through long trips on open water.
A classic example is the Current Designs Squall GTS ($1,550). At close to 16 feet, it has the perfect profile for good cruising speed and easy tracking. It sits low to the water to resist wind, and has good stability in surf and swells. For better control, you can deploy a rudder from the cockpit. The Squall has a comfortable padded seat for long days, and its bow and stern hatches offer enough room for overnight gear.
Or, check out the Wilderness Systems Tempest 170 ($1,600). It’s a touch longer than the Squall at 17 feet, and its combination of initial stability (when you first sit in the boat) and secondary stability (when it starts to roll) makes it a great choice for stormier open waters. Its seat is fully adjustable, and if you need it you can drop down a skeg. Three hatches offer room for a week’s worth of gear.