well, i'm 16 so i realize my opinions are prob different than a 14 yr old's.. but for me, disney is all about the rides- running from ride to ride trying to fit in as much as possible- and the trip is less about the dining experiences. a character dinner is nice once in a while, but for the most part, i would rather not spend a ton of money and a ton of time on eating.. so overall i would say yes, a character meal would be fine, but not necessary.. and no more than one per trip.
also, my 14 yr old sis seems to agree with me on this
but again, everyone is different.. my mom for example loves the character meals (its her only chance to relax lol.. i keep the family running around for most of the day haha)
sorry for the lengthly response lol
bottom line, i would ask your 14 yr old what she wants