In October 1999 (already 10 years ago), Mélanie and I did a 12-day trek to the Annapurna Base Camp. This site provides a good summary of the trek.
For a short trek with few altitude problems, the Annapurna region provides you with unparalleled access to spectacular horizons of snowy peaks, so high that you'll find yourself looking twice before you believe that they are not clouds. As well as providing the views for which the trek is famous, the trail takes you through an ever-changing landscape of rice fields, misty forests and tiny local villages.
On October 10, 1999, just before we reached the British Expedition Annapurna South Face Base Camp (4234m.), I proposed to Mélanie. I could swear that the rock on which I had her sit when I popped the question is the one pictured below. With the thin air and lack of oxygen, I figured I had a better chance of her saying “yes” to my proposal. :)