Considering the atrocious reviews of the St. Regis Monarch Bay, my vote is the St. Regis Los Angeles.

Minutes away from Beverly Hill shopping & Westside activities and very mindful of Platinum status.

I have stayed there twice using awards and have been very pleased.

There are a number of threads on the St. Regis Los Angeles. I would search for others to get a wide range of opinions.

http://www.flyertalk.com/forum/Forum74/HTML/000846.html