It's clearly written into the T/Cs that you can't.
From
http://www.hyatt.com/gp/en/benefits/...ip_diamond.jsp
4 For purposes of this award, a suite provides for one-bedroom accommodations. Suite upgrade award is not valid toward Specialty, Premier, Presidential or Diplomatic Suites. Suite upgrade may not be booked at Hyatt hotels or resorts before they have opened. Suite upgrade is available on paid nights, for a maximum of 7 consecutive nights; excludes Park Hyatt Beaver Creek Resort , Park Hyatt Sydney, Andaz Tokyo, Hyatt Regency Phuket Resort, Hyatt Regency Tulsa, Hyatt Regency Wichita, Hyatt Key West Resort and Spa, Hyatt Manila City of Dreams, Hyatt Santa Barbara, Hyatt Place , Hyatt House , Hyatt Residence Club properties or M life resorts.