Salkantay Trek was absolutely amazing. The day hiking over the pass was incredible and exceeded my expectations. It was very difficult but as long as I walked slowly I didn't get so winded and it was much easier than I thought it was going to be.
It was a delight to walk through so many ecological zones in one day, from grasslands to alpine to cloud forest and everything in between. It was along day from before sunrise to after dark but tremendously rewarding.
I would do this trek again in a heartbeat. Next time I would spend more days in Cusco to acclimate.