I'm not really finding a straight answer on this, though I admit I often seem to think I'm out-of-the-loop where others seem to just know the obvious.

I have always used my employee discount (Ritz, Marriott, Hilton) to get inexpensive rooms, but I think the next step in my FT history is the BRG. On the BRG Blog, (which is an AMAZING read and I can't wait to add this to my toolbox) they just seem to use TripRewards/Wyndham properties. Is this because Hiltons, Marriotts, Starwood, etc. don't work? What gives?