Stonehenge has changed a lot since I was there last. It used to be in the Y formed from the junction of the A303 and A334 roads, but they've actually removed the A334 (there's a round about that takes you there a little further up the A303, and you go down that road to then back track to the Stonehenge visitor's center). So you still crest a hill while you're driving on the A303 and see it ahead of you, but everything else looks different.
We got the English Heritage Overseas Visitor's Pass while we were there. It basically makes you an English Heritage member for nine days. It's well worth looking into if you're going to a place with a lot of ancient monuments - English Heritage tends to be in charge of places that are in ruins, so you can quickly pay back the entrance fees if there are a bunch of those around.