In reply to robhf:
We did part of the Santa Cruz trek as an approach route to Alpamayo and it was nice. Sometimes it looked a bit crowded but the scenery is amazing.
If you want to visit the Machu Picchu it's a very good idea to stay one night at Aguas Calientes. The village itself is boring but you can take a minibus to Machu Picchu early in the morning and avoid all the crowds. You'll avoid most of the hikers too because they start to arrive around 10am.
Machu Picchu is amazing place early in the morning when it's empty of tourists. It gets a big circus later in the day so it really is a good idea to get there early in the morning.