I stay at the Westin 6-10 times per year, if they aren't sold out when I am in Palo Alto.
On my last two stays I have received suite upgrades, once to a fireplace suite.(very nice) and once to a guest office suite (not bad, except the TV doesn't quite face the bed so unless you are an albatross, you can't really change channels lying down).
On the second of two recent stays, I was informed that I was being upgraded to a tower suite but that my room would take a few minutes to finish cleaning (I was told the room number). An hour later I was finally given my room keys to find that it was actually a guest office. Not bad, but for the hour back I would have taken a regular room instead. I was really looking forward to a tower suite so that I could claim a presence in all known room types at the hotel. It's the little things that make me happy
Matt