Hi!
There are some good examples in this web site about hotels, hostals, etc.
If you want to go to a child friendly restaurant try in "El Parque de Atracciones", "Centro de Ocio Opción" (Alcorcón, Metro Sur) and you've also have the typical fast food restaurants: Friday's, Foster's, etc.
There are some good places in "Príncipe Pío", etc, Well, it's full of them, really

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