Anyone recommend anywhere in Wiltshire that can be reached by bus from Swindon? [Obviously Avebury area is always the default possibility].

I was just looking at Stonehenge area, having found there is a bus from Swindon to Amesbury via Durrington. My (unused in the field) Explorer map is covered with highlighting, but there seems to be very little of it that is accessible? Is this right?

Where would one start with an impromptu, middle-of-a-rainy-Saturday bus-reliant trip to Stonehenge? Is it completely pointless as an idea? Would I get frustrated by the people and the difficulty of actually getting to see any of the monuments? Which is the best way to approach? etc etc etc.

I'm sure this has been covered on other threads but there's too many to search and almost all the current fieldnotes seem to involve cars...