I prefer to reserve via the diamond account, but "combine" points to get an award using points from the non-diamond account. This makes it possible for them to plan on accommodating my best room guarantee before I arrive and possibly comp a suite upgrade.
see:
http://www.hyatt.com/gp/en/awards/combine_transfer.jsp
Originally Posted by GOLD PASSPORT POINT COMBINING REQUEST FORM
POINT COMBINING TERMS AND CONDITIONS:
You may authorize the combination of the necessary number of Gold Passport points from your Gold Passport account with those in one other specifically designated Gold Passport account in order to qualify for a specific award. To book an award reservation using combined points, call Gold Passport Customer Service at 1-800-30 HYATT or your nearest Hyatt Worldwide Reservation Centre. A completed Gold Passport Point Combining Request Form must be signed by both members and submitted to Gold Passport Customer Service, P.O. Box 27089, Omaha, NE 68127-0089, USA, or faxed to 1(402) 593-9449 in order to combine the required number of points for the award issuance. Forms are available by calling the Automated Account Information Line at 1-800-51 HYATT or on goldpassport.com. Outside the U.S. and Canada, phone 1 (402) 592-6433 or your nearest Hyatt Worldwide Reservation Centre. The award may be issued in only one member’s name. Once the award is issued in the designated member’s name, the member who transferred the points will relinquish all rights to the combined points. Only the number of points necessary to redeem the specific award may be combined.