Just yesterday, I purchased an annual travel policy from GeoBlue (Trekker Choice) primarily for its medical evacuation coverage of $500k and $1 million in medical coverage. It also comes with a 24/7 Global Medical Assistance benefit. GeoBlue was the only company I could find that would insure longer duration trips (up to 70 days) in an annual policy.
We paid $390 for the policy, and it could be money well spent or money flushed down the toilet (I'm hoping for the toilet), but the policy offers great peace of mind while traveling.
And for trips longer than 70 days, you can easily buy a rider from them for the additional days. (Because of this, if it is close, we try to stay under 70 days, but typically we fail every other year....)