I have retained Gold regularly for last 5-6 years by taking advantage of HH's regular fast tracks to Gold with 4 stays in 90 days.
I stay mainly in Europe, Africa and Asia.
In Africa and Asia Gold is great.
In Namibia, I even once got upgraded from a regular, non exec, room to Diplomatic suite at Hilton Windhoek for a five night paid stay. I was also upgraded in Joburg, Cape Town and Windhoek again from base room to Exec room.
In Asia, I have been upgraded every time in Conrads in Bangkok and Hong Kong as well as upgrades at Hilton Sukhumvit and Millennium Hilton in Bangkok.
In Europe, things are not so good though. I was upgraded once or twice at Hilton T5 but I do not recall any others and I have stayed at nearly every Hilton in London.
So if your future travels take you to Asia or Africa I would say is well worth it. In Europe I don't see the value. In America, I imagine the value is even less.