The Beatles.. definitely.. another good example of Major-minor is in their song "We Can Work It Out".. The song was great already and then John decided to add a minor section to contrast with the happy Major section, the opening line of the bridge starts with "Life is very short and there's no time.."
When I talk about Music Appreciation to people, they sometimes think I simply mean listening to music.. or listening to music I wouldn't normally listen to. That is partly true.. but what I am really doing is ACTIVELY listening. Most people just passively listen to the music, even if they are singing along themselves. Actively listening to a song means that you are looking for all the different parts that make up the song. It can be very technical, very spiritual/meditative or a combination of the two.. but it definitely isn't just listening to a song for the pure enjoyment of listening to a song.
When you listen to artists, such as The Beatles, listen to the song passively for the first couple of times you have heard it.. and then from that point forward, actively listen to it and get as much as you can from it.