The usual great Hyatt experience
We arrived at 8:00 am on a Sunday morning after an Alaska cruise. The front desk associate, Cassie, got us into a king room on the 29th floor immediately. She also took the time to give us great tips on restaurants (such as a less crowded location for the enormously popular Pike Place Chowder right across the street) and activities. Our room was clean and spacious. My only slight complaint is that the bed was a little soft for our taste. A nice touch is an automated window shade that will block as little or as much light as you wish. Additionally, you can control it from the bed. 
We have a Hyatt Visa card and were offered a free upgrade to the Hyatt club on the 27th floor by the Hyatt corporation. The Hyatt grand club is a great benefit of the Hyatt chain. There are free soft drinks, bottled water, fresh brewed coffee, tea, etc. available all day. There was a breakfast spread that included smoked salmon, pastries, bagels, fresh fruit and more. Additionally, they have locally sourced cold cuts and hot appetizers at lunch and dinner. 
Hyatt offers many upgrades for either an additional charge or points. I believe their points program is one of the most generous and best values in the business and has sold me on the Hyatt brand.
as pertains to the Grand Hyatt Seattle, we would definitely stay at this location again.