Journey is such a special game. And the other player is such a key element to the experience. I've played it a few times and each time felt so different based on who I was playing with. First time I actually just wanted to do it alone (I'm usually really not a fan of multiplayer), but after spending most of the journey with another player I finally understood why it was important. The second time I played from start to finish with the same veteran player, who guided me to all the secrets I didn't even have a clue existed, and we were constantly chiming to each other (that musical sound you mentioned). They were much more patient than the first player and by the end it was amazing how much emotion I felt having to part ways with someone I didn't even know. And I'll confess too, I cried on that second run.
Third time I must've had some connection problems because the other player would only be there for a little while then disappear, replaced by another later that would also disappear. When I finished the game by myself, it truly felt like a lonely experience. A beautiful, but sad lonely experience. But even after that time I would still 100% recommend it.
I haven't played Last Guardian or Curiosity, but Last Guardian I've definitely been meaning to try, and Curiosity I haven't heard of but I'm always a fan of games that put beauty before hardware longevity.
Yes.