The walk from the Park Hyatt to the nearest White House gate entrance is like 15-20 minutes for me. The Grand Hyatt walk to get me to the same kind of place is like 10-15 minutes. The Hyatt Place is like a 5 minute walk.

I personally tend to prefer the Park Hyatt; but as a tourist with Hyatt Diamond status, the Grand Hyatt makes pretty good sense if you're doing the Metro rather than taxis.