The exhibition centre is actually pretty good. I took a few kids there recently and it really helped them understand how neolithic people might have lived. It was expensive, but we had a really good time.

National trust are awful though (although I believe Stone Hedge is actually English Heritage). Anyone interested in seeing a more authentic neolithic site would be better off visiting one of the many free to access long barrow and hill forts.

Stoney Littleton Long Barrow is one of my personal favourites. It's a lovely walk to the site and the site itself is beautiful and completely free. You can even explore the barrow and touch the stones.