I know lots of people who have been up Silbury at some time or other - there was an experiment with musical instruments up there a few years back. The reason I likened climbing Silbury to our societies attitude to smoking in public places was to illustrate that what was acceptable and normal a few years back is now almost taboo. Attitudes change with the wisdom of hindsight.
I agree with the person who said Silbury is best viewed from afar - when it suddenly appears almost mysteriously in the landscape and sometimes creates an illusion of moving with you as you walk along somewhere like the Wansdyke. I also recommend (for those who can) a walk up to Harestone Down Stone Circle which can be accessed along the White Horse Trail. Whether this actually was a stone circle is questionable but I personally think it was. If you stand there and look back you will see in front of you West Kennett Long Barrow with Silbury perfectly aligned behind it. You can even see Windmill Hill. And to one side sits East Kennett Long Barrow suddenly taking on a prominence maybe not noticed before. Whatever Silbury was constructed for it seems to be a pivotal focal point in an archaeologically amazing landscape.