There is a great section about the Yellowstone super volcano in Bill Bryson's book "A brief history of everything". Pretty much no spot on Earth would be safe if this one erupted - probably an extinction event.
Lots of places would be safe during the eruption - just probably not the United States or southern Canada. Humans have survived many super volcanic eruptions before.
The real problem if you survive the eruption would be the decade or so of crazy weather and food shortages, not to mention general unrest.
