Dave ... have to agree regarding Avebury .... Stonehenge is far to crowded and organised to have any 'feel' left .... Avebury has atmosphere in spade-fulls ... especially if you hit it at the right time and have it pretty much to yourself (and it's nature means it can absorb a few folk without feeling like disneyworld)
Rich ... it is intriguing that they sourced parts of the henge from places far away ... and at a time when transporting anything wasn't a trivial undertaking (let alone a bloody great stone) ... wasn't done for nothing, or on a whim ... but I guess we'll never know why for sure, just theories hatched from millenia later and a cultural world away.
K