If you can get the 777 on the route, it's not a hard upgrade, especially for Platinums. I have never missed the upgrade on the 777 on that route, regardless of my elite level. As a Platinum, it has consistently cleared at five days out every time I've flown the 777 on that route in the last five years.

I've missed upgrades on smaller equipment as a Platinum many times, including the 762 when traveling on a fairly high fare class.