At Chantilly? Typical Hyatt Place breakfast, just like the one I had in Fremont yesterday morning (cereal, bagel/toast, juice, yogurt), and the rooms were clean on all my stays, and wi-fi worked perfectly. I haven't ordered any of the hot items to comment on those. As I've been there on weekends or holiday periods (3 times this year) never a crowd for breakfast. I'd stay here again if I book into or out of Dulles, as it's easy enough to get there from DC with public transit, and I do like the restaurant options within walking distance compared to Hyatt Dulles.

The one thing I have noticed at other Hyatt Places is there are "peak" times for breakfast, generally 9am-10am on weekends, where it can get pretty crowded and become an obstacle course, particularly if you're trying to select and toast a bagel (Rancho Cordova and Fremont experience this). I don't do weekday stays to say if it's the same on that side.

edited to add: HERE are all the photos I took there this month.