Current first year at Bath, currently living in the Quads.
Social life and general type of people living in each accommodation block is nigh identical, it's a mixed bag of people wherever you happen to choose. That said, I would really recommend going for on-campus accommodation over city accomodation, both in terms of access to lectures (heard the buses can bea bit of a nightmare) and access to the SU and sports village for social stuff. The length of the campus can be walked in less then ten minutes, so physical location is not a big deal at all.
Having an ensuite is a luxury I've personally quite liked, but again, it's a luxury, and often at the expense of room space. The shared toilets are reasonably well maintained and from what I've heard it's not really a major trouble.
As for green walls, I know that Marlborough and Solsbury do not have green walls, I haven't been inside Woodland to know if they do. The Quads have some green fittings, but we also have moodlighting! You can change the colour and everything! I don't know why. It might be the second most confusing and useless thing I've experienced at Bath, after trying to attend a 9:15 lecture after a heavy night.