According to the commentary, Naveen took some time to find the perfect voice actor. After reaching three possible candidates, they brought in their female staff to listen to each actor. Bruno Campos had the biggest "swoon" factor.
Flynn Rider from Tangled was designed when the directors gathered up every female animating for Disney, tacked pictures of celebrities and princes to the wall, had them analyze which specific features were the most attractive, and created Flynn from that. It was called, I kid you not, "The Hot Man Meeting".
Prince Hans in Frozen, Anna even engages in some non-sexual Eating the Eye Candy with him. Actually an example of Evil Is Sexy. Kristoff is also designed to be rather appealing, particularly more evident when compared to his earlier, more child-like designs.
On the subject of Dreamworks, they gave us Pretty Boy Jack Frost, to the point where he has in-universe fangirls (Toothiana and her fairy helpers, since humans can't see him). He's handsome, has piercing blue eyes, is a confirmed badass, is endearingly mischievous, and has a soft spot for kids, all wrapped up in a tragic backstory and tied with a bow of I Just Want to Be Loved. Yup, that'll do it.