American Beauty was more or less a 90s answer to The Graduate. A main character who has a comfortable American Dream life that he doesn't like the direction of. A cross generational affair. A moody soundtrack. It's a good film. I wouldn't say it changed me. If the white picket fence life is good enough for Scott Bakula why not everyone. But its quirky, fraught, eroticism in the suburbs appealed to my idea that there is potentially magic in everything. 'look closer'. It's unashamedly voyeuristic - even the guy at work who is insulted by Lester voyeuristically wonders how Lester can have so much passion. It seems a cop out. If Angela wanted him and he wanted Angela where is the harm? But maybe he realises he'd only be trading one American Dream for another.
Dead Poets Society - not a lot of people went to see it at the cinema actually (nor me). It was the year of Batman.
But it does convey a mood very well, probably largely thanks to Peter Weir's direction and how it reined in Robin Williams as well.
I also loved him in Mrs Doubtfire. It conveyed that caring instincts are not something that have to be exclusively feminine.
But it was arguably Jack Nicholson as The Joker who had the most affect on me in the cinema. Larger than life, dancing to Prince, dispensing literally cutting wit (the pen is the truly mightier than the sword) he was 'Pop Art' and pop star personified which appealed to part of my Leo exuberance.