I'll jump in here rather than start a new thread.

When is the best time to purchase Ambassdor?
Got 2 x weekend stays in San Francisco in December (paying cash).

The second one would benefit from a 4pm checkout as I have a late flight, although I could keep myself occupied if need be.

May have another couple of night in Sofia (Bulgaria) in January.

Is it best to wait until as close as possible to the stays, or is it best to allow a little time for updates to be reflected. Not sure if the hotel could fill up in the meantime?
Happy with what room I've booked, so if no upgrades, it won't be the end of the world. 10k compensation is probably of more use ultimately if a benefit couldn't be delivered.