Eraserhead
I walked ot of the theater wondering why I wasted my time. Three weeks later I realized that most of my daydreams centered around wondering what the hell was going on in different scenes of the movie.
I became fascinated, saw it again and loved it.
Attack of the Clones I do not htink it is a great movie, and I don’t love it, but I certainly liked it much better on a second veiwing. Don’t know why, probably because the first viewing was “This is gonna rock” and it didn’t., And the second was, “Why am I wasting my time watching this agina.” and I enjoyed it.
A.I. This movie annpoyed me when I first watched it,but now I think it is a great film. And I don’t buy the argument the Spielberg ruined Kubrick’s vision. Simply not true.
Alien 3. I hated this movie for years because I thought it was too much of a generic horror movie and was too depressing. But the main reason was I used to be the worlds biggest Aliens geek and I was pissed off that there were no pulse rifles, no motion trackers, only one alien, and they killed off survivors of the previous movie during the opening credits.
After seeing the disaster of Alien Resurrection, I watched Alien 3 again and had changed my tune. A3 still wasn’t a great movie, but it had a LOT of things that AR lacked… As well as a very dark, tragic theme about loss and redemption that I totally missed because I was too hungry for non-stop action. The Extended Edition adds over half an hour to the movie and smooths over some of the extreme choppiness of the theatrical release, and even makes honest-to-goodness characters out of the faceless parade of bald prisoners that made up the cast.
EZ
Fight Club. Hated it at first, but it grew on me.
Monty Python and the Holy Grail for me.
It was my first exposure to the Pythons (this was in the mid-80s). Had a few chuckles but mostly didn’t get it. And what’s with that ending?? 
Bought the dvd recently. I had a laugh-fest.
Memento. The first time I watched it, I was so confused and could not understand any of it–the characters, the plot, anything.
I watched it a second time and it made total sense to me, like a lightbulb had gone off in my head. Though that might have been the pot talking. :^P
Well, I just watched Squirms of Enqueerment (it’s Shirley MacLaine day on TCM). I didn’t violently loathe it and feel like I needed to scrape my tongue off like I did the last time I saw it, 21 years ago. But I still don’t love it. I will never understand how Deborah “The Worst Actress on Two Feet” Winger ever got the reputation she has, but MacLaine’s performance was only about 90% as annoying as I remember it. And I still have an embarrassing crush on Jeff Daniels.
Why does James L Brooks only make chick flicks? His TV work wouldn’t lead one to expec that, no?
Death to Smoochy
Another vote for 2001: A Space Odyssey. The first time I watched it I was seventeen and I fell asleep during it. Two years later I watched it again and I loved it. I think the reason why is the second time I watched it, I had a better appreciation for movies.
Another one for me: Army of Darkness. The first time I watched it, I found it dull and cheesy. I didn’t understand that it was supposed to be cheesy. The second time I watched it, I found it hilarious. Now we own the special edition on DVD (can’t remember if it’s actually called special edition or something else).
Oh, and off-topic: Someone recommended Bruce Campbell’s autobiography in another thread. I finished it last week. Even more amazing, my husband, who rarely reads books, actually read it before me, even though I’m the one who bought it.
Another vote for Monty Python and the Holy Grail. I thought it was weak compared to the show. Now I laugh like hell every time I see it.
Also, The Piano. When I first saw it, I thought the script was decidedly amateurish, but the movie crawled inside my head and wouldn’t leave. I had to see it again, and when I did I loved it.
And Star Wars. I wouldn’t say I didn’t like it, I just thought it didn’t live up to the hype. But Lucas’s sets, and Harrison Ford’s performance, and the groundbreaking (for better or worse) special effects made up for the kind of lame plot, and the holes in same. So I grew to love it, although now I’m kind of tired of it.
If you are uncool then I must be the king of uncool 'cause that was the most boring pile of steaming crap I have had the misfortune of watching.
Driving Miss Daisy. Yes, Driving Miss Daisy. Walked out halfway through the first time I attempted to watch it – there was no goddamn story! Just a bunch of stuff that happens! Then, after it won the Best Picture Oscar, I gave it another chance and watched it in a different frame of mind. Still don’t know if it deserved that Oscar, but it’s a great movie. Mostly due to Morgan Freeman: “I’m trying to drive you to the store!”
WILD AT HEART
THE LAST TEMPTATION OF CHRIST
They both just seemed to drag on and on!
I actually apologized to the friends I watched WAH with. Then two days later, I watched it before I had to take it back to the rental place & found that I was really getting into it.
LTOC also drug on, plus the volume had to be turned up & down, plus I was nitpicking all the theological AND novel-to-film inaccuracies (yes, I’d actually
read the book when the project was announced under the title THE PASSION
& Aidan Quinn was Jesus & Sting was Pilate). A few months later, I watched it,
I think on HBO or some such movie channel, and was drawn in by the moments
of intensity & depth I’d missed the first time.
I’m almost afraid HOUSE OF 1,000 CORPSES might join them. I’ve only happened on the last half twice on cable- first time I utterly despised it, second time I despised it but thought “this does have some moments!” (the liquor store,
“I’ll remember you” by Slim Whitman, “Who’s your daddy?” and the midnight
procession.") Dear God, please don’t let me ultimately like that piece of crap! L
LOTR TFOTR.
I didn’t think it was brilliant the second time but it got much better the second and third.
Mission:Impossible.
Magnolia.
I couldn’t bear to watch Lost In Translation the first time, let alone the second (which I did twice over). The most pretentious self-indulgent peace of crap I’ve seen for a long while (flashes of Three Colours Red roaming my mind).
Believe it or not, Dr. Strangelove. First time I saw it, it just put me off, for some reason I can’t fathom now. A ‘comedy’ about global thermonuclear war? Slim Pickens as a B-52 pilot? The climax consists of a bunch of stuffed shirts arguing in a poorly-lit room? WTF?
Then I caught bits of it again, and realized the brilliance the direction and of the performances, particularly by Peter Sellers and the great Sterling Hayden. I’m better now.
A Clockwork Orange
After I saw it the first time I was sort of like “Hm. Okay.” and went on with my day. Within a week I was itching to see it again, and now after having seen it several times I am decidedly a fan.
Mulholland Dr.
Made me angry the first time I saw it; I was so frustrated that I couldn’t understand what was going on. But I’ve learned to relax and appreciate the film without worrying that It has no comprehensible plot.
I agree about Time Bandits
I disliked Last Action Hero the first time I saw it, but now I think it’s one of the 2 best movies Schwartznegger has ever done. I just had to realize that it wasn’t an action movie.
Well, you see, it’s a cop-out. 
Punch-Drunk Love. The first time I saw it, I was to distracted by the seeming randomness. I didn’t know how I felt about it. When I saw it a couple of days later, I knew that it was wonderful. It was like watching a person’s mindset acted out on the screen.
Lost In Translation is often mentioned in threads like this, but I have to say it’s one of my favorites. It captures perfectly the self-induced melancholy of sitting in a hotel bar in a strange place.