There wasn´t much to see/do in Huanchaco - we just used it as a base to visit Lambayeque, where we visited the Tumbes Reales Museum, which showcases the Royal Tombs of Sipan. These are Peru´s version of Tuntakhamun´s Tomb, as they were found untouched by grave robbers, and yielded some very impressive gold artifacts.
We also visited the nearby ruins of Chan Chan, the largest adobe city in the world, built by the Chimu Empre in AD1300. We also visited the Moche temples of the Sun and Moon. The temple of the Sun is the largest pyramid in the Americas, and was constructed of 140,000,000 adobe bricks. The Spanish, in their quest for treasure (which was successful), diverted the Rio Moche to the Pyramid and washed away two thirds of it. The temple of the moon has some nice polychrome reliefs.
We spent the night in Trujillo. Not much here either, besides the unusual reed boats used by fisherman (available for hire) and some very nice ceviche, a traditional South American dish of fish cooked only in lime juice, and served with onion and chilli.