To be honest, if I was shooting a family portrait, I would not have used something as "busy" as the castle as the background. With that sort of background, especially being so sharp and with the sun in their eyes, it's going to be almost impossible to get it to not look like a snapshot - nice, sharp and contrasty, but still a snapshot.
If I had to use the castle as the background, I would have done almost anything in my power to get the sun out of their eyes and behind them, ie, shoot at a different time of day, use a scrim, shoot from the other side of the castle, composite a better lit photo of them with a photo of the front of the castle, etc. I would also try to use a lower f-stop on my lens so that the DoF was more limited and the background went slightly soft.
If none of the above was in the cards, then, in post processing, I would try to lower the contrast, lower the saturation a bit, soften the shadows on the family, and draw the viewers' eyes to the family, not to the hyper-sharp background. I would also warm up the background and remove the overhead wires. Maybe something like this quick and dirty tweak. This version is much less flashy than the original, but, IMHO, in a direction starting to be a bit more appropriate for a family portrait.
If I had more time I would remove the people in the doorway (as discussed earlier), and I would also square up the castle walls a bit better (probably need to do this independently of the foreground subjects). I might even apply a painterly effect and print the image on canvas to distract away from the problems caused by the busy background.
Just my $0.02,
Tom
PS - Mods: On PSG.com, it seems that fairly awful artifacts are always introduced when a full rez submission is down-rezed for display. This is one of those images on which this is obvious. Is there any work-around or any other way to improve the displayed version?