[Closed] Family Routes in Beacons / Cambrians?

So we're off on our hols next weekend - vague plan is to point the van in the direction of Wales and spend a few days in the hills (Beacons / Cambrians) before heading off to our favourite camping spot in Pembrokeshire.

We'd like to take time out for a full day family bike ride en route. Little 'un is in a bike seat so nothing too technical / steep and ideally traffic free.

I was thinking perhaps the upper bit of the Taff Trail. Any recommendations for the best / most scenic sections?

Any other routes in the area we could have a go at?

EDIT By Cambrians I'm referring to the bit between the Beacons and Southern bit of Snowdonia that never became a national park... would probably look to camp a couple of nights near Rhandirmwyn.