The Hay-on-Wye Literary Festival does not need much introduction but an enthusiastic festival-goer noted how brilliant it is for kids. Also remember the Beyond the Border Wales International Storytelling Festival, which gets great reviews from all attendees.
If a full-on Literary festival sounds a bit much, Hay-on-Wye is semi-twinned with the HowTheLightGetsIn music and philosophy festival from the Institute of Art and Ideas. Mr Scruff, Andrew Weatherall and others entertained in 2014.