We did the Salkantay trek (4 days) and really enjoyed it. The guide, food and landscapes were all wonderful. We were served coca tea in our tents every morning as our wake up call which was a nice touch, and the guide helped us with any altitude sickness we suffered from.
The only downsides were that I would've preferred to get a bit more information about Incas and Peruvian history on the tour, and the camping wasn't as "in the wilderness" as I'd expected, but this might be to many people's tastes - just not mine ! Otherwise I'd recommend this tour.