I'm staying in Hanoi for a week longer than I anticipated and need an interesting place to go within either a 6-8 hr. or so ride (or even a short flight). I've been to Sa Pa twice previously and also done Halong Bay and was looking for something similar in uniqueness for this 3 day weekend. Any suggestions as to where might be a very interesting place to go or thing to do for 3 days (i.e. meditation retreat, spa, horseback trek etc.). Thank you all for your ideas.