I'm refining my itinerary a bit:
Day 1: arrive Cuzco 800am, take it easy - lunch and then taxi to Ollantaytambo (night in Ollantaytambo)
Day 2: morning train to Machu Picchu, return on late afternoon train to Cuzco, dinner and stay the night in Cuzco
Day 3: Explore Cuzco in the morning, fly to Lima, afternoon sights and dinner in Lima, stay night in Miraflores (nearer the airport)
Day 4: 6am departure LIM-MIA-DCA