The most common method I've seen is to run the discharge hose to a mechanical air gap mounted on your sink platform. This looks like a chrome knob on the sink deck with about 3 horizontal vents cut into the side. The vents should always face the sink so that if it overflows (they do sometimes) the water goes into the sink.
From the air gap, the ideal place to waste the dishwasher is into the garbage disposal, and most disposals have a knockout fixture just for this purpose. The most compelling reason didn't occur to me until recently, and that is that the dishwasher dumps a whole lot of really great hot soapy water and what better place to put it than into the disposal where it helps to keep it clean and grease free. From the disposal, the water goes to the ptrap and off to the sewer.
If the cabinets aren't in yet, you can run the dishwasher discharge hose under the cabinets (behind the toekick) so you don't have to see them from the front. Given the cabinet is 18", I'm wondering if it is a drawer stack, where you can just run the hoses on the back of the cabinet wall behind the drawers. Make sure you secure the hoses well so they aren't pinched or snagged by the drawers.