The Miller collection has an interesting connection to Washington 2006 because it contains the only other known example of the 1c "Z" Grill.
One is on display at Washington 2006 as part of the William H. Gross exhibit and the other is at the National Postal Museum.
The National Postal Museum's Philatelic Curator Wilson Hulme has put together a guide book of his personal favorites in the Rarity Revealed: Benjamin K. Miller Collection exhibit.
Among his favorites is a complete set of imperforate Columbians. Believe me, to see them in person was a quite thrill .
To download the Rarity Revealed curator's tour guidebook, click here.