Peru and Machu Picchu

Assuming that 'Inca Trail' is not a random one of the eight zillion, but the one that starts from the Cusco - Aquas Calientes railroad:

Where are you from? Have you hiked at altitude before? How are you with a lot of elevation change in a day - - are your knees sort of still intact? If these answers come out pretty good, go for the Salkantay over the Inca for better raw scenery.

If you want to get both the basin and a trek, do the short (two-day ?) version of the Inca. The whole Inca system is pretty over-populated, however.

Either one is going to be nippy at night - - a good bit below freezing in July, mostly.

Is there still time to book a tour/guide?

Hiking the Inca Trail TO M.P. (a few days, max) is a highly regulated business, to minimize ecological impact. It requires advance booking with specific providers, who employ porters and approved campsite procedures. I haven't been, and I'm not remotely suggesting it's too fancy or the right price for you. I'm just warning that you probably are too late to book it!

Thanks for your answers. We're from MA., so, no, we have never hiked in altitude. We are giving ourselves 3 days to acclimate before we start Salkantay Trek. The Inca Trail is booked thru Oct. I'm doing it with my 2 boys who are in their 20's and in good shape. Knees pretty much intact for all of us. We're not new to hiking, but have never done 4 days in a row.

Bengay. By the bucket.

Since your boys are in their 20s I'm assuming you're in your 40s or 50s? I am your age and do a lot of hiking in the high Sierra Nevada Mountains here in California. Altitudes ranging from 8,000 - 14,000+ ft. My strategy for dealing with altitude is to drink LOTS of water for a few days before you arrive and while there. You will most likely deal with altitude sickness while there, especially if you are from a place like MA that is relatively close to sea level. Headache and nausea are the most common symptoms. The water will help with that a lot but I also bring along the strongest headache medicine I can get my hands on and start taking it a day before I get to altitude. I keep taking it for at least 24 hours after I get up above about 8,000 ft. Make sure to keep eating good protein and carbs. This strategy usually gets me through the beginning without a problem.
You are going to one of the most difficult places in the world to hike due to the steep terrain and the extreme altitude. Be very mindful of how you feel and don't push yourself. Stop frequently and hydrate constantly.
Have you bought medical evacuation insurance for your trip? I would never travel to a place like the one you are going to without it - for you and your whole family. I'll spare you the stories of friends who have gone to remote places like Peru without it and had trouble but you need to make sure to purchase this well in advance of departure.

the rainforest you mean the amazon area? it's not a bad choice - you can stay in a lodge for 2 nights to see animals and do some hikes in the forest, or boat tour on the river. 2 yrs ago I went to Puerto Maldonado and it's only a short flight from cuzco. If you haven't been to Peru I'd also suggest you look into lake titikaka and the colca canyon. both are fascinating places. 10 days may not be able to see all of these, you need probably 2.5 to 3 weeks. i'd go to cuzco/mp + titikaka with 10 days.

I've hiked in and around Machu Picchu but not the Salkantay Trek. The pictures of it are spectacular and you are healthy now, so do it. The jungle can wait. Incredible sights.

I just returned from a trip to South America and visited Machu Picchu (May 26th). After talking to a few people I decided not to hike the Inca Trail because it sounds like a lot of people do this now and you are always surrounded by other hikers (and this is how it looked as we passed by them). I decided to take a taxi from Cusco to Ollantaytambo and catch the train there to Aguas Calientes the night before I planned to visit Machu Picchu. The next morning I caught the first bus (5:30am) and got to Machu Picchu as it opened at 6am. We passed many of the hikers and were the first people (just a small handful) to get to explore the site. I also schedule in advance to hike Wayna Picchu which offered great views.

I personally would spend more time in the Amazon area and then use the train for Machu Picchu going a day earlier than you plan to visit the site. This way you don't have to rush the Amazon and you will get to see Machu Picchu easily. I also recommend booking your train tickets in advance because they can fill up and it would be horrible to get stuck.