Lovely review of one of my favorite films. I quite agree with the broad strokes of your idea of hopefulness, but I'm interested in your take on Richard's suicide, which I don't view as stemming primarily from his frustration with the party. I had the sense throughout the buildup that he had been planning to end his life and trying the best he could to prepare his friend for that necessary eventuality, which for him was also about hope.
Back before effective treatment for HIV disease, the end stages of AIDS were awful. I had many friends who nurtured the hope of a dignified ending not centered around helplessness, pain, and strangling to death from the pneumocystis pneumonia that was proximate cause of death for many.
When I watched the film for the first time, I could hear their voices and see their thoughts behind Richard's eyes. Part of the genius of the film for me was the communication of Richard's suicide as hope and not despair.
I guess that's a dark message, but those were dark years to live through.