In reply to David Best: Having just done the Manaslu circuit and the Annapurna circuit, I would say go to the Khumbu and do the 2 passes more mountains and you dont get to walk on verey dusty roas on the Annapurna circuit the road gos all the way to Manang but only saw jeeps to chame then the road starts again after the Throng la pass.
you could alwas do the Annapurna base camp or one of the more remote areas depends what you want.
I think doing the everest 2 passes is the best for mountain views If you dont like lots of people go out of the usual trekking season I am going back out in 4 weeks so hopping its going to be quiter as It was verey funny listening to people complain about hot showers and no log burner at hi camp on the throng la pass.
what ever you do take it slow and give yourself a couple of extra days just in case of bad weather getting sick or transport problembs..