Moon River is seriously such a contender for the best song of all time. So timeless, heavenly and exquisite. If you were to choose to listen to only one song for the rest of your life, having this one as your choice should be more than enough.
Katy/her team is really setting her up for failure later by pandering to kids, imo. She's almost 30, in a few years she'll look completely desperate/out of touch to that demographic (not that she doesn't already). She should be pandering to the early-mid 20's crowd instead.