North Korea is similar to Bhutan, takes some advance planning and typically closes to tourism during the winter months, but the agencies do everything and flight availability is not a problem. Koryo Group is the big one and has plenty of interesting tours that no one can match, but my time was short I went with a cheaper, standard solo tour from Asia Live. I went in May 2010 and the agency was able to put the trip together and get the visa in under a month.

Everything transits to/from Beijing, so a double-entry China visa is required.

Since everything is set and deviation is extremely hard, plus communication with the outside world so constrained, it was perhaps my most relaxing vacation.

Of open ones on your list, I particularly enjoyed the Roman ruins, desert and even the cities (particularly Constantine) of Algeria.