vincewy

I just redeemed and burned all of my award miles (for flying during dead/second membership year).

BOS-IST (or to many points in Western Europe through IST) is 45000 for I, indeed very good value. Upgrade from Y to J using miles, not so much, as you're paying miles using seat guaranteed rates and it's the same 45000 miles, you'd be better off using E+ upgrade vouchers.

Regional flights to Gulf regions, 12500 for Y (X) and 17500 for J (I). Again, depending on aircraft. I redeemed DXB-IST for 17500 miles (I fare bucket), almost guaranteed widebody (either 777 or A330), this is actually even better value than North American segments using I fare as the flight is about half of flight time to NA from IST. OTOH, for MCT-IST, I might be neutral to both Y and J as J may be blocked middle seats on narrow bodies.

As a caveat, availabilities for I on North American segments are ridiculously scarce with the exception of IAH, YUL and BOS, nonexistent for LAX and JFK.