I went to Bhutan in 2010 with http://www.jojos.com.bt/ and had the most fantastic time, but maybe that's because I was with a Nat Geo photographer.
You can see some of my photos from that trip here http://www.flickr.com/photos/simonmonk/sets/72157631231413904/
Bhutan is in fact it's my number one place I'm looking to return to.
Couple of other outfits I'm looking at:
Have a great trip. Wonderful country! about 8 years ago