20's - Metropolis (I've never seen any of the contenders, but this seems to be at the top of all of the lists and it intrigues me...would like to see it)
30's - Gone With The Wind (Tossup with Wizard of Oz, but I leaned toward this because of the great acting performances and heavy material)
40's - Citizen Kane (Tougher call than I thought, but it is considered possibly the greatest movie ever and changed a lot about film-making)
50's - 12 Angry Men (Lots of good options here, but this movie has always been a personal favorite of mine, brilliant in its simplicity)
60's - Psycho (I'm not a horror fan, but its Hitchcock's masterpiece and this decade seemed lack to me for some reason)
70's - Godfather II (Too many greats here...tough to decide, but went with my personal favorite)
80's - Breakfast Club (Another personal favorite...feel like it capsulized the decade well and was funny and endearing)
90's - Pulp Fiction (I don't care if Tarantino borrows his style from elsewhere, this is the first time I'd seen anything like it and loved it...masterpiece, IMO)
00's - Lord of the Rings: Return of the King (Epic story on paper done justice in film...beautiful)
10's - Inception (I feel like this is a weak choice, but we have 6.5 years left and there are a lot of good ones I haven't seen yet)