I'm new into classic movies, please suggest me what to watch

I've been watching some classic movies lately, last two were It's a Wonderful Life (I was delighted!) and Waterloo Bridge (I liked it, but I was so sad after watching, it ruined my day lol).

Honestly, I prefer profound movies with happy end, like It's a Wonderful Life :) (but I would also be okay with something just fun and enjoyable)

Please suggest me some really good movies :)