Really glad this topic came up! It sent me back to the long-abandoned search. First, I learned that at this point, no one is selling an annual policy in New York State...but I don't know why.
Second, an agent at AIG pointed out to me that for what I'm looking for (not to insure the cost of the trip, but rather to deal with interruption, disaster or medical emergency) it's cheaper to buy for each of my trips than to buy a year.
As it turns out, covering me (age 72) and my wife (65) for our December 16-day trip to Chile costs $86 total...well worth it.
We weren't interested in covering the trip cost, because it's all in airline miles (which can be redeposited) and reservations (to be paid in-country). For a trip with a big upfront expense, like a cruise, I'd probably think differently. In any case, thanks, Jon!