I would personally like to see that UUs did NOT cause golden age. I never use some of the earlier UUs because I really don't want a despotic golden age with three cities! This of course causes trouble, as then the only way to get a golden age would be with wonders - so some nations might not get a golden age at all. Would this be such a bad thing? The golden age could be more of a reward than something that you will have sometime, but you have to carefully see when. It could also be connected with the overall happiness of your civ, your wealth etc etc.
It could, though, cause some different effects apart from just increased economy and production. Perhaps militaristic civs would get an attack and defend boost, commercial civs an economic boost, scientific a science boost and so on. Then if you were commercial/scientific, your golden age would be similar to the current one. If you were militaristic/agricultural, you would have stronger units and bigger growth, or some such. It's a fine idea - I would like to see the golden age-concept developed further in other aspects too.