In reply to JuanTinco:
the two clees are dead close - Brown Clee is marginally higher, with far fewer people but a longer and harder walk from wherever you can leave the car, while Titterstone Clee has a car park at 400m or so. its bare, but has fantastic views to the Black Mountains, Radnor and Brecon Beacons.
more people on the summit, but its a massive hill and you could easily do a 9km round trip and only see people in the car park...
the Stiperstones are great - you can see Snowdon on a very good day, again, get away from the honey pot summit and its empty. that said, i've been there in decent weather and sen less than half a dozen people the whole day.