Hmmm... I used to go to the movies all the time, but I don't see all that many these days. Here are a few all time favorites off the top of my head.
Grumpy Old Men
Grumpier Old Men
( I REALLY loved Jack Lemon and Walter Mathau )
Moonstruck - the more times you see it, the funnier it gets. Especially if you're an Italian from Brooklyn.
Lord of the Rings - get the extended DVD's. You'll understand a whole lot more...
And probably not on too many people's lists, but they get my vote:
Powder - I don't think this did too well at the box office, but I really enjoyed it.
Dances With Wolves - I hate Kevin Costner, but this was an excellent film IMO.