I didn't realise that golds and diamonds were entitled to upgrades to suites at Hilton Garden Inns. But now I see the terms and conditions say:
"At Hilton Garden Inn hotels, Diamond VIP members will receive complimentary continental breakfast each morning for the member and one additional person throughout the stay or a $5.00 coupon* for use during stay at the Pavilion Pantry® (excludes alcohol) if upgrade to a suite is not possible. *Coupon cannot be redeemed for cash." Has this condition changed recently?

Having said that, as gold and diamond, I have received upgrades on 4 occasions to suites and full breakfast at the HGI at LAX, El Segundo, but no other HGI. At Hilton hotel brands, there is no requirement to upgrade to suites , but have received upgrades to oceanfront suites at the Hilton Key west, Hilton Waterfront, Huntington Beach and Fess Parkers Doubletree resort, Santa Barbara. It seems to depend on each hotel. Some give the minimum, while others treat us exceptionally well. I'll certainly be more prepared in future to ask at Hilton Garden Inns.