I was actually staying at Grand Hyatt Erawan when the GC manager mentioned Hyatt Place was opening. So I changed to Hyatt place (instead of Marriott Marquis) for one night.
I recognized some of the staff from GH Erawan. There were 9 guests checked-in on the first day, and each of us were given a cert of being their inaugural first guest. Bottle of Chandon was waiting in the room which was a lovely touch!
Assuming the back-lit signboard is up and running already, Hyatt Place is across the street from Ariston Hotel (purple sign).
Beds are slightly hard. The best beds I have slept so far is surprisingly @ Aloft BKK
Breakfast is ok. Missing an egg-station. Hopefully they will check out other hotels breakfast offerings. Take note that officially breakfast ends @ 0930H, which is bit early IMHO.
If you like taking a long shower, the shower stall may get flooded.
If you are walking along the sidewalk to Phom Phrong BTS, be careful of stray electrical wires.
It's great to see another Hyatt option in BKK, but with so many hotels nearby, it is going to be tough. Marriott Marquis is my new goto hotel, esp if you have Platinum status.