I stayed at hostels a bit in Europe in my youth, and having recently spent a nice weekend at a UK YHA with our kids it's got me thinking more about the value of that kind of accommodation for us at the mo - where there's often communal outdoor space and other kids to run around in it with, games room/pool table etc, meals sometimes provided if required but also self-catering kitchen etc.
So I'm after recommendations please, for really great hostels in the UK and mainland Europe for families with kids ca. 9-12yrs, and ideally some activities or running-around space on site (or great locations in terms of proximity to interesting sites).