If you are coming solely for Machu Picchu, I think it's worth it. Take a red eye to Lima, spend day 1 in Cusco. Day 2 Sacred Valley. Day 3 Hike the Short Inca Trail. Day 4 Machu Picchu and back to Cusco. Day 5 Head Home. If you're coming from the U.S. you will likely have little to no jet lag to get over (Cusco was in the same time zone as the Eastern US, but I don't know if that will always be the case with the US switching to permanent DST). This makes it a lot more do-able for a quick trip than some destinations.