thanks guys. Like those ideas. In terms of the waterfalls, I've done sgwyd y eira, and the ones before that, not sure how high I have started previously
In that case, try the waterfalls on the Nedd Fechan from Pontneddfechan - start and finish from the Angel in Pontneddfechan, and walk up as far as you like. Ok, it's an out-and-back, but it's a great place.
Ok, how about parking at Penwyllt and wandering up into the Ogof Fynnon Ddu National Nature Reserve - limestone pavements, more shake-holes than you can shake a stick at.
or parking on the Trecastle road at about SN855223, walking up to Llyn y Fan Fawr, then ascending Bwlch Giedd, walking round the escarpment to Fan Foel or further depending on your speed, then coming off Fan Foel (or futher) and circling back to the car along the bottom of the escarpment.
Depending on what side of the Beacons, up to Fan Fach lake then up onto ridge and follow along. Down to Fan Fawr lake and around the bottom returning to the start.
It comes via the trout farm up the track.
I'm away at the moment so can't get the grid references but i'm sure Kate will help.