Glad to hear the positive feed back, any great tips to share???
We were on the trip in Oct 08 and it was fantastic!
As previously mentioned, the hotel staff and people are quite friendly. Our guides really took care of us and went out of their way to talk to everybody and make them feel welcome. (They also took us bar hopping, but that may be an adult trip thing) We found the trip to be casual, quite a bit of exercise (esp with the higher altitude) and there was a good variety of things to do. We got along fine bargaining and throughout the trip with very limited Spanish too, which was one of our concerns.
I don't think this has been mentioned yet but there's a double decker bus tour that just started (last Oct). From your hotel in Miraflores (the first day in Lima) you'll see a yellow clock tower which is about five minutes from the hotel which is Kennedy Square (plus a Starbucks, KFC and McDonalds). The MiraBus leaves from there and a little further in, there's a little stall (they'll speak English) to purchase tickets.
There's tons of food on this trip. Full meals, all the bottled water you'd want and little snacks in between too. You get two non alcoholic drinks per meal, we picked a bottled water and Inca Kola (tastes like pineapple bubblegum soda) or a coke most of the time. The first group meal at the weaving center was pretty yummy, very flavorful mashed potatoes

We were also served alpaca (several times) and guinea pig and let loose for a couple of meals (armed with maps that our guides circled restaurants suggestions).
Photo ops galore. Watch for the giant hummingbirds on your morning walk to the breakfast buffet and smuggle out an apple and visit the horses at the Sol y Luna
Definitely bring layers, we were there for the rainy season (Disney provided ponchos, yay!) The first night was outdoors and there's a cooking demo later on that are outside and it gets a little chilly although they set a fire and there's heating lamps.
Watch the water intake. Bottled water good, tap water not good. Keep your mouth closed during rafting

We had two people feel a little queasy the following day and probably swallowed some water. The hotel, guides and the Machu Picchu sanctuary had meds for any tummy issues as well as oxygen for altitude.