I don't wish to give the impression that it's a bad car for the motorway- not at all.
Perhaps I hadn't appreciated what a great car the Alhambra is for long motorway journeys- I was actually really looking forward to using the golf on a long run- for a change, we didn't have kids with us and had a choice of car.
Much of this is really about expectations.
If I consider my car history, I started with hot hatches- then had 2 alfa saloons and 2 BMWs- during the years that I was doing heavy motorway mileage. The 205 became a bit tiring on long runs between Manchester, Birmingham and London.
Now I have the luxury of choosing the appropriate car for whatever use.
But the golf ( i'm talking 7.5, I appreciate OP is mainly interested in mk8) is a perfectly good car for long runs- just not as good as an oil burning bus!