No priority security line. You don't really have time to do too much. You could take a cab over to the Marriott - about two miles from the airport. You could hang at the beach there (it's pretty) and have a meal at Duke's, which is adjacent to the beach/Marriott.

You could also cab it to Hamura's Saimin, a noodle shop that takes you back in time to what Hawaii must have been like in the 1950s. Very inexpensive. Also known for their lilikoi (passion fruit) chiffon pie.

Otherwise, there is not much to do in Lihue (there is also a museum there).

If you wanted to rent a car you could drive to Kapa'a - there are beaches along the way and have lunch at Bubba's Burgers. You could also drive the other direction and go to Koloa/Poipu - about a 20 minute drive. There is Puka Dog, the beach, Lappert's (ice cream) or shopping in Koloa village, Kukuiula Village or Poipu Shopping Village.

You can google any of these places to get a little more information about them to determine whether you'd be interested.

Unfortunately, it's not quite enough time to do any serious sight seeing or activities.