I like the route Lonely Planet Hiking Hawaii recommends for Alakai Swamp:
Kalalau Lookout trailhead > Phea Lookout > Kilohana Lookout. And back.
That’s maximum bang / mile, I think.
It’s a brilliant hike, too, by the way. Don’t be deterred by the name “Swamp”.
OK, it’s a swamp. But it’s so weird and unexpected after the sunny, hot coastal beaches, that I was instantly won over. Many hikers are. For some it’s their favourite hike on Kauai.
The highlight is not the swamp. Not pounding miles of boardwalk in my running shoes.
Some come specifically to see indigenous Hawaiian flora and fauna.
But for most, the highlight is the drop dead gorgeous 4000ft vista looking over Na Pali (The Cliffs). One of he great lookouts in the world.
see all my photos from this hike on flickr
learn more – Alaka’i Swamp Trail – Trailspotting