Agreed, we stayed here during December 2024 on points with a SUA over a weekend no less, and was looking Dec 2025 and did not find anything. Demand is very high at this hotel during xmas markets season (even through Jan 6/Epiphany) and points reservations during this time may be a think of the past. Cash rates are $1K+ during December also, and several other hotels I've looked at are sold out for the month already.

OP - if you must use Hyatt points in Vienna in December, Andaz Vienna has standard room and suite award availability on Sunday Dec 13 and deluxe suite availability (30K) on several other dates in December. It's a nice hotel and if you are going for xmas markets it is very easy to grab a tram into the ring and walk around and you'll be mostly out and about all day. It's also right next to Vienna Central Station which is how you'd get to Bratislava for a day trip. I think the Deluxe Suite is an ok use of 30K/nt during one of the busiest months in Vienna. I stayed here recently and I thought the buffet breakfast was very close in food quality to the PHV.

Personally if I go back to Vienna for xmas markets I'll probably look to stay in the Altstadt at a reasonably priced non-hyatt hotel like Steigenberger Hotel Herrenhof. Great location and not outrageously expensive.