Le Guin prose is exceptional and would be nearly impossible to bring to screen well. I'm sure it will be tried at some point. Maybe a dark horse, but I actually think The Lathe of Heaven might be the most adaptable. It's the simplest story and has plenty of room for exciting changes and visuals in a film.

Her Earthsea book was actually adapted. By Studio Ghibli no less. It was so bad that the dad of the director left the theater halfway through to have a smoke. Said dad was no other than Hayao Miyazaki (Director of Spirited Away, Howl's Miving Castle, Castle in the Sky, etc)

I just finished The Disposessed and found it critiqued both the capitalist and anarchist society. The people of Annares have simple happiness, but they starve and strive to keep the society alive. It's also very explicit that it only works because they don't uphold their anarchist ideals and coerce everyone into work through social pressure.

I think a film would work and would present a "you could have a different society, but it would never be a paradise" type idea.