I have stayed at the Coconut Plantation a couple of times. It is not the best part of Kauai (IMHO) to stay, but it isn't the worst. It is a bit over-developed with a big shopping center adjacent to the several hotels there. You will be about 45-60 mins away with decent traffic from Princeville and the northern part of the island. There are several nice hiking trails near the CP too. The drive to Waimea Cyn will be a bit longer - about 60-90 mins. For a nice evening meal, try Coconuts, which is a 5 min drive to Kapaa.