Nepal - yeah it's stuffed with tourists but even the more popular treks are still worth a visit. Don't bother with UK based agencies, they just stitch you up. It only takes a day to sort out your permits in Kathmandu then you're off on the teashack trail. You'll be putting money into the pockets of local people, not suits back in your own country, and get a greater sense of satisfaction when you're finished. Email me if you'd like more information.