The official line from the Hhonors T&Cs is:
The following brands do not offer complimentary upgrades: Embassy Suites™, Hilton Garden Inn®, Hampton Inn & Suites®, Homewood Suites by Hilton®, Home2 Suites by Hilton®, and Hilton Grand Vacations®.
Of course, this being Hilton, every property interprets the T&Cs as they see fit, and this is one of the instances where it can actually work in your favor. Some HGIs upgrade guests who have status; I have encountered it several times.
Originally Posted by
BobH
Usually there isn't much to upgrade to, at best a room in a quieter part of the hotel.
If you are referring to the low-rise, airport-type properties, then I would agree with that, but I have had some pretty nice junior suites and true suites at urban HGIs.
Also re: breakfast, make sure that your MyWay benefit is set to it for HGIs. And, even if it is, you might have to argue. Twice this year I have had HGIs claim that I didn't have the breakfast option selected and that I wanted the 1,000 points instead. When pushed, one of the properties actually admitted that they didn't even open up my personal profile, but that instead that was their standard assumption, that Diamonds would want points instead of breakfast!