If you really need to stick to Starwood properties, I would actually recommend the Sheraton Miyako. It has a brand new club lounge that is pretty good with newly renovated rooms which are very pleasant as well (unfortunately I don't think plats get upgraded to renovated rooms). These renovated rooms, IMO, beats any rooms at the Westin hands down.

I find westin to be too expensive for its offerings, especially when it's often double the price of the Sheraton. I also didn't like the old world feel of the westin, which has no Japanese elements whatsoever. While the Sheraton also feels old, at least it feels Japanese, complete with a rather tranquil Japanese garden.

Depending on when you're staying, there's a new LC property coming soon, but it seems to be very very expensive. If you don't have to stick with Starwood, there are plenty of far superior options in town - Aman, Andaz, Park Hyatt (feels a bit old too, but timelessly old), Manadarin, Conrad to name a few. Of course, these hotels aren't cheap and are definitely in the ballpark of the future LC property.