Great to read everyone`s thoughts!
I agree about Bhutan - well worth the effort (and money) - we flew from KTM and out to IXB. That was cheapest. Nowadays though, any agency will arrange travel - so its not really 'difficult'
Belarus I visited in 2002 (when I was 21), on a transit visa from Russia to Poland - man... the booze was cheap back then in Belarus.
Dominica - its easy and relatively cheap to get to from Antigua and Barbados on LIAT.
Another one that was sorta hard was Turkmenistan - but I finally found a great agency to do the paperwork.
I would imagine, for the Americans, it also may be hard to go to Iran since you have to go on a tour - but again, well worth the effort. What a fantastic country.
As for vacation, it helps to be in education, and unlike my underpaid colleagues south of the border, we get treated pretty well up here.