Discussing this at work today - there are endless dystopian futures, but not so many utopian options. I've read:
The Dispossessed (definitely my favourite utopia novel, hence the username)
Woman on the Edge of Time
News from Nowhere (not that great as a novel IMO)
Acts of Destruction by Mat Coward (nice change in that it's a socialist rather than anarchist utopia)
I'd love any other recommendations :)