I watched Rear Window and North by Northwest.
For one of the most highly-rated films of all time on iMDB, I found North by Northwest somewhat silly. The character of the lead protagonist was extremely cliched, but I suppose it's the era that the film was made. It was OK, overall, but I don't want to watch it again. Wanting to watch a film again is my personal measure of whether or not it's a good film.
Rear Window was really good, I though. Quite psychological and unpredictable. Again, the lead character was somewhat cliched, but I definitely want to watch this again.