I wanted to get here the first time I saw the amazing pictures of it in a National Geographic magazine! To actually see it was the epitome of what a "Bucket List" experience is all about--why we write/update one! WOW!
This has to be one of the more challenging sites to get to/from --not counting the long international flight--that we have ever encountered. It ended up being a 3 day adventure. We had to fly to Cusco, enter the Sacred Valley, stay overnight, take the train to Machu Picchu, take the bus to the site and then do it all in reverse! The great part of the tripis that there is so much to see and do along the way that it is all a great adventure.
One part of the trip that we were unprepared for is the bus ride up the mountain. My wife suffers from altro phobia, and this ride pushed her to the limit. So much so that we did not return for the second day (early in the morning when there are no crowds) at the site. However, we both felt that we had seen and done all that we needed to do on the first day and wanted to sleep in the next day.
In terms of what we did: all the lower levels, climb the STEEP stairs to the top (where the views and vistas are nothing short of incredible and ever changing with the clouds), the walk back down through the buildings without their roofs to get to the bar for a drink and to enjoy the wonderful views of the mountains.
Details of note: the Peruvian authorities have strict visiting rules that limit guided tours at Machu Picchu. The time slot is critical--DO NOT MISS IT! You are limited as to what you can take into the site--bring water, but no plastic bottles or any food. There are NO BATHROOMS on the site--only at the entrance (for a small fee) and you can't return! Do not bring small children--the 8,000 feet can make it tough for them and the stairs are too high. Some (most) of the paths are one way and they do get after you! Recognize that all the beautiful changes in the views are weather related--it does get hotter/colder as the day goes on. Be prepared with clothing for ALL POSSIBLE CONTINGENCIES!
There can be many people at points of interest. Try to "map out" what you absolutely want to see in advance and KNOW HOW YOU ARE GOING TO GET THERE! Study the site map. Be prepared to be amazed--it is better than you could ever imagine.