I have been Platinum for several years and have had some good things happen on the hotel side but nothing at a Timeshare. The concierge room is nice and as someone mentioned early in the thread it varies considerably by location. Excellent in Manhattan, for example; not so much at the Marriott in Overland Park, KS. It is nice to have a lounge to get away to other than the hotel bar.
I once received an upgrade to a two level room at the Marriott in DT Minneapolis upon a walk in check in - no reservation. I also recall the customer service rep telling me I was bumping someone at the Cosmopolitan in Las Vegas when I procrastinated and there was nothing available online. Also at the Cosmo, there is a separate room to check in which is fun to be treated special, but also can save a lot of time depending upon when you check in.
I usually use the points when someone - a friend, a family member - needs a room. One day, I will take that trip around the world.