In addition to Groundhog Day, my top five are:
1. Casablanca
2. Caddyshack
3. Bonnie & Clyde
4. My Fair Lady
1. Casablanca
2. Caddyshack
3. Bonnie & Clyde
4. My Fair Lady
1 Casablanca (Now I want to watch it again)
2 Rear Window( beautiful story telling by the masters camera)
3 Hitchcock's Vertigo, North by Northwest, the first hour of The Birds and Frenzy , all for the same reason(great camera shots). As long as I'm cheating I'll throw in Dial M for Murder:)
it's hard to narrow it down to five but here goes:
4 The Bridge on the River Kwai
5 The killing ( an early kubrick movie)