I am also from SEA (PH) and for what it's worth, you're not the only one getting unplayable ping recently.
I have observed something odd though, the lag seems to be just for instanced content. I tried boneskinner today and got 1.6k ping, but when I jumped out and tried LLA in timberline falls, it seemed normal. I also ran around to do the open world dailies with no issue.
Another weird thing is, some of my friends (also from PH) have had this issue since last year, and have quit the game because of it. It'd be nice to have the stability back.