"The American Heritage Dictionary of the English Language (Fourth Edition ... care) that 'la-la land' is apparently named after their city?"
"It's so named because of Hollywood and the film industry. The definition is not totally accurate, though, because the movie producers are not only unrealistic in their expectations, but they are deadly serious as well."
No, it's so-named (back in the '70s as I recall) due to the new-agey, and other crazy attitudes and life-styles existent then and there.