A classic Peru route: Lima (2–3 nights) → Sacred Valley/Cusco (3–4 nights) → Machu Picchu (1–2 nights) → return to Lima. Flights from Lima to Cusco save 24–30 hours of bus travel.
If focusing only on Cusco/Sacred Valley/Machu Picchu, seven days is tight but possible. Add time for acclimatization to high altitude (Cusco is 3,400m).