Haven't seen much activity lately on this thread so wanted to post my experience. Everything that is detailed before is accurate:
-bathrooms have marble soak tub and separate shower- very luxurious
- valet is $$, however parking after 4 or 5p goes down in the parking garages nearby
- lobby is gorgeous, granite and marble accents throughout
- lounge on 27th floor is adequate sized, poor selection of beers however (either Miller or Bud)
- amenity was Robert Mondavi wine bottle and garlic boursin cheese - very good quality for both
- automated shutters were cool, found them better at blocking out light than Wynn in Las Vegas
- high ceilings and windows- had nice view of Space Needle so resisted urge to close window shades
- bedroom area small, but rest of Executive Suite was nice- seating area with flat screen TV and wet bar with mini fridge
- marble throughout! marble foyer, marble bathrooms, marble bar counter top, even the wall lights looked like marble

- health club is 24 hour access and nice wood floors, sauna and steam room close at 9p however

Following Grand Hyatt Tokyo, this has been the Grand-est Hyatt so far. I had to check the stationery on the desk twice to make sure I was at a Hyatt!