With the high suicide rate, the addiction to passive entertainment, the isolationism in most persons in the culture, the repression of thought, feeling, and community, I don't see how F451 could represent a utopian society.

I think it is probably definitionally impossible, as others have noted. In "The Matrix", Agent Smith explains to Morpheous tht the first Matrix was what the agents felt would be a utopia -- no crime, no disease, no hatred, no war, etc. But man went nuts. The presence of conflict is what creates meaning and growth. Without them, man is sterile and has no depth. There is no happiness in an insipid, thoughtless, passive existence. The agents, had to recreate a society that included these "problems" in order for man to be happy.

I would be hard-pressed to imagine Bradbury, with his focus on knowledge, personality, free thought, etc., could possibly see the culture represented in F451 as a utopia. It is, rather, a dystopia.