Mount Everest with prayer flags
Going to Mount Everest is an experience that will leave you in awe of how big everything is in the Himalaya. Sleeping at 16000+ feet is without a doubt a highlight not to be missed when in Tibet. Make sure you are reasonably fit and spend many nights along the way to help acclimatize to the altitude. Bring gloves and a hat - your fingers will stop working in short order when it's cold.