The trip to Cajamarca from Trujillo is a bit long, but a phenomenal ride which is a great illustration of the Coastal zones and of the Peruvian Sierra.
Pacasmayo is a great destination for those who are looking for a quiet weekend at the beach. The city is small with a Plaza de Armas (or city center) which sits right on la playa.
Travel in Peru is highly centered on public transportation. The people here travel mostly by automobile, whether its a bus, a micro, a taxi, or a collectivo. It is much more common to take a bus out of the city for the weekend rather hop in your own personalized SUV.