Yes, the fence at Stonehenge is a distraction.
Alternatively, to walk among the stones, I suggest a stop at Avebury Stone circle which is open at any time.
http://en.wikipedia.org/wiki/Avebury
Mad Max provides van tours of both Stonehenge and Avebury from Bath.
http://www.madmaxtours.co.uk/
-Paul
I did the Mad Max tour from Bath last July, and it was great. I was expecting a BIG FENCE at Stonehenge. Instead, it was a little rope around the perimeter of the stones that I didn't find at all distracting. Avebury is much larger, but the stones are spread over such a large area that you'd need to view it from the air to see all of it.
I am sorry I'll just be passing through the UK as I change planes at Heathrow next May.