Unfortunately almost all the tourists travel only to Southern Peru although there are many interesting archeological sites in Northern Peru and none of them are too touristic if you avoid Holy Week&Fiestas Patrias (Independence Day in July).

Day trip to Chavin (~3 hours from Huaraz) can be done easily from Huaraz and there are also some archeological sites in Cajamarca. If you have time, I would recommend travelling to coastal city of Trujillo. The architecture is beautiful in downtown and there are many impressive and important archeological sites very close to the city. Chan Chan & Huaca de la Luna y Sol can be visited easily during the same day. Chiclayo is another coastal town with important archeological sights (moche museum in Lambayeque, Ferrenafe etc) nearby. If you had more time, Chachapoyas would be interesting option (impressive sights, very few tourists).

For planning your schedule I would recommend investigating the transportation options between Cajamarca & Huaraz. My last trip to Cajamarca was ~3 years so my information can be out of date but you might have to travel via the coast...