Hello there,
I spend so long on this site I thought it was about time I registered, and this post seems as good a reason as any!
I work for the National Trust at Stonehenge Landscape, so I've managed to do a few special access tours. The one shot I've always found my best was perching the camera on the fallen stone 55 and facing towards the north east. This gets a nice view of stone 55 at the bottom of the pic, and the remaining 3 arches of the outer sarsen circle in the background. It was a cold grey day when I took it, but it still looked good.
The inner side of the trilithon stones 53 and 54 have the carvings of the Mycenaean dagger and axe head on them (can't remember which of the two stones it is now), as well as some more recent antiquarian era tagging. Opposite them, but on the outer side of stones 57 and 58 you can see small plugs concealing bolts used to repair the standing stones. Not very photogenic though! Stone 16, part of the outer circle, has some of the best dressing work on it, especially viewed from the SE side (I think).
You can get a fairly good plan halfway down the Wikipedia page for Stonehenge.
Regards,
Steve