What can I say about this country that hasn't already been said? During my 4 trips there (to date) I have experienced the awesomeness of the world's highest mountains, especially trekking the Khumbu (Everest) region around Gokyo Lakes and the hike up to the Annapurna Base Camp. 
The mountains are just one (very important considering the plethora of trekking available) aspect of Nepal though, with UNESCO sites littering the country, photogenic & friendly people, historic and religious (Hindu & Buddhist) towns and villages and as a biodiversity hotspot there are also safaris in the South of the country to take you on a discovery of tigers, elephants, rhinos, red pandas, wild water buffalo and crocodiles. Plus many of the most gorgeous birds to be found in Asia.
This is all to say nothing of a laid back atmosphere that encourages relaxing and people watching from within the confines of many cool restaurants and bars, some with quite spectacular views.