There's a Frank Zappa song 'We're Turning Again' that sums up a lot of stuff - but here's 'where it's at' (the cutting edge, as they say) http://www.iol.ie/~geniet/callanish/index.html Even just sitting behind a monitor and capturing a sequence of images from one of these webcams, on the day, is vital.
Gwenhyfar's Chair catches the most southerly setting moon, from the Houghton Common stone circle. (This is implied by the name too).
Where are the northern alignments ?