I'd start with the Renaissance Era animated films like The Little Mermaid (1989), Beauty and the Beast (1991), Aladdin (1992), and The Lion King (1994). Beautiful classic 2D animation style, and great music from Ashman and Menkin.

If you enjoy them and want more, you have the option of going back to the Classic Era (e.g. Snow White and Cinderella) or ahead to the Revival Era (e.g. Tangled and Frozen).