[Closed] Help - recommend me a circular walk in the hills

My father would have been 81 on Sunday but unfortunately he passed away peacefully 13 months ago, and with all that has happened since I have not been out in the hills to "clear my head", although I have the chance to do so this Sunday.

He loved the Brecon Beacons and very nearly retired to the area, so my natural inclination is for Pen-y-Fan but I already know it well and there must be some other, equally beautiful walks nearby. Since I am heading down from Surrey I don't want to go further afield than South Wales (I'm 3 hrs drive from Brecon), and the walk shouldn't be more than 3-4 hours long at a good pace.

Any suggestions? Many thanks in advance!

R