Visited 15th April 2003: We had quite a bit of difficulty figuring out which rocky outcrop was which, but in the end I think we got to Carn Meini. It's an enormous mass of stones, all higgledy piggledy. You look into it and see standing stones and burial chambers all over the place, but they're not real, just natural coincidences that look extremely similar to the real thing.
We had a snack at Carn Meini, then William insisted on climbing to the highest bit he could see. Children know no fear! This place would be a good stopping off point for slightly older kids because they could roam around and explore (without stressing their parents out too much).
This page is from the Trefach Campsite web site and contains amongst other things a panorama of the view from Carn Meini (the page calls it Caermeini or Carn-Meynen depending on the mood of the author!).
This is by no means an excellent example of a panorama, but it's the only one of Carn Meini I'm aware of. Java support is necessary if you want to see the view.