What is your favorite Hyatt in Europe and why?

I am hoping to head to Europe this summer and have a couple Category 7 Free Night Certificate burning a hole in my pocket. I have an open itinerary for a few days and would like to go some place and splurge on a great property. Probably a Hyatt property unless there is an exciting SLH property that can't be missed. Hyatt doesn't have the biggest footprint in Europe I know.

I'm a Globalist traveling solo. I couldn't find a "best of Europe" thread elsewhere, but if there is one I'm happy to merge.

I've heard good things about the Park Hyatt Vienna. I've stayed at the Andaz in both London and Amsterdam and loved those.