The best and most stomach-wrenching way to see the Nazca lines is by taking a tour in a small prop plane. There are also a couple of places along the Inter-American Hwy where you can pull out and climb a nearby hill for a vantage of the odd markings.
From Nazca take the Carretera Interoceánica north through a series of small towns to the city of Ayacucho for an ascent of around 2,500 m over about six hours and 340 km. There are plenty of hotels and hostels in Ayacucho and you’re likely to be pooped after the long trek up from sea level.
From Ayacucho, depart going south on Ruta 3S. Follow 3S for the better part of 560 km all the way to Cuzco. There are plenty of opportunities to detour and a couple of nice lakes along the way. But the 3S offers some extremely twisty sections so you don’t have to be particularly creative to enjoy an exciting ride.