MeltwaterfallsWhile in the Sacred Valley, a jaunt to the outskirts of Cuzco is probably worth your time. Surely, you will visit Sawsaywaman? If time permits, a moderate hike beginning at Tambombachay
(arrive by taxi) and ending at Saqsaywaman can be done in a bit more than 1/2 a day. For me its still a highlight I remember well from my trip in 2010. The walk is 12 miles, but its not too strenuous if you walk often. Besides the 4-5 historic stops along the way, the scenery on a pleasant day is pretty stunning.
Tambombachay to SaqsaywamanRegarding
Qhapaq Ñan, one site that's a bit off the radar,
(but CLEARLY inscribed based on the dossier) is
Raqchi which can be organized as a planned bus stop between Cuzco and Puno. I loved exploring the relatively modest site because the environment and structures are quite unique. As others have stated
Pachacamac is also worth the trip while your in Lima.