try and pick up a copy of Prehistoric Avebury by Aubrey Burl, its a great book about the monuments in the Avebury area, and links comparisons with other areas such as Salisbury Plain. It mentions WB in a number of contexts as well as other 'lost' monuments in the area. Might give you a wider understanding of what was around the area, and what was contemporaneous with each other.

johan

ps, its a good read as well!