If you stay in Machu Picchu Sanctuary Lodge, you can not come back to Aguas Calientes at night, so you have to pass your time in your hotel. It is not that bad though. They have a very good bar, and you food and drink is usually included in your room charge, so you don't have to pay anything, just eat and drink. But it is still boring to most of the people. But the good thing is that this hotel is very expensive, so most of the people can not afford to stay there. So they stay in Aguas Calientes (few miles from Machu Picchu ruins). Aguas Calientes is really colorful. They have many restaurants, and if you like pizza, then I can say you will pass a good time there, because all the restaurants try to sell some sorts of Pizza in Aguas Calientes.
There are few bars exist in Aguas calientes. Most of them offer drinks buy one get four. Though sometimes prices are four times higher than those of Cusco. Also many of them will offer free pisco sour, but mind it, it is not a free glass of pisco sour, you may call it a sample, as it is actually a tiny cup of pisco sour.
You will find most bars in Ave Pachacutec. Ampu stays open late. Big brother, El Uno Mas, Tezao Restaurant and Bar, Wasicha is located clse to Plaza, and you can dance there till late hours.
If you like open air drinks, go to Tezao, located at 2nd floor with open terrace.
In Aguas Calientes late hour means 10/11 pm, after that you will not find much places to go. Bear or drinks are not sold there after 11 pm. Most of the people store their energy to wake up early in the morning for Machu Picchu ride, so you will see many people after 10/11 pm.