Cusco v Trujillo?
Cusco. This will give you a glimpse into the ancient cultures of the Inca. It is the gateway to Machu Picchu, the Sacred Valley, and the Andean countryside. Beautiful textiles, fun parties and Incan tradition mixes with Catholic ritual. Beautiful Andean landscape. Culturally rich.
Trujillo. Colonial architecture. Beautiful churches and buildings. The historic ancient capital of the Chimu culture: Chan Chan. 20 minutes from Trujillo is Huanchaco, perfect for anyone who wants some beach time.
I personally recommend Cusco if you’re going to spend extended time in one of these 2 great cities. There is more to do/see and it will be more culturally diverse.