Enjoy your trip in Peru with Salkantay trekking . It allows you to see the great Salkantay Glacier at about 4600 mt of altitude and the Laguna .
Moreover, continuing the trekking, you can see the forest along Urubamba river before arriving at Machu Picchu site, it is marvellous. We visited Huayna Picchu too, wonderfull the sight from that site.
Salkantay trekking was great also for food and kindness of the staff .
I would like to suggest one only thing, maybe the five days four nights tour is too much.
I think it is enough only three days trekking you will enjoy Machu Picchu in any case.