+1
When staying in the U.S. or using award booking, I usually register for 2 adults. There's no difference in price.

"During periods of high demand access to the Regency Club or Grand Club lounge may not be available; therefore, complimentary full breakfast for each registered guest and 2,500 bonus points will be given. Not available at Hyatt Place™, Hyatt Summerfield Suites™, or Hyatt Vacation Club Resorts."
http://goldpassport.hyatt.com/gp/en/...ip_diamond.jsp