Nothing has changed.
I still recommend Sheraton Grande Sukhumvit.
I guess the stuff others have recommended is also still in place. Can't imagine the Sukothai brunch going down in a rush..
Oh one new thing I discovered: JW Marriott Bangkok has pretty solid F&B overall and now I see that they have a JAPANESE Sunday brunch. So rather than being international, the focus is everything Japanese. Option to upgrade to free-flow of bubbly also exists.