Wow! Thanks so much for the very informative response.
My suspicions are confirmed.... that I have a very hard decision ahead of me. :O haha
I personally care virtually nothing about shopping while traveling, and other than a splurge here and there, I prefer to eat more affordable at casual / local kinds of places. I've been to so many big cities, and I feel like once you've seen a few, you've seen them all. I'm not much for touristy things, other than to see them, marvel, and move on. Experiencing culture in a city is why I love going to a new place.
If the Design Hotels collection honored the SNAs / breakfast benefits, or if the Old Clare were a cat. 4, this would be a no-brainier. But I feel as though the OC property is definitely more of what I'm looking for. I'll be traveling / staying solo in Sydney to meet with friends here and there, but in that sense, I suppose I don't really NEED a suite... (ha... status and points and miles have ruined me...)
I suppose I'll go with my gut and go with the Old Clare......... but maybe I'll wait until the SNA gets confirmed at the Westin just to see what I'm really comparing.... haha.