If you liked the Gossip Girl series try…
A-List (series) by Zoey Dean
Alice, I Think by Susan Juby
The Au Pairs by Melissa de la Cruz
The Boyfriend List by E. Lockhart
The Clique by Lisi Harrison
Crunch Time by Mariah Fredericks
The Earth, My Butt and Other Big Round Things by Carolyn Mackler
Gingerbread (and Shrimp) by Rachel Cohn
Heart on my Sleeve by Ellen Wittlinger
If I have a Wicked Stepmother, Where’s My Prince by Melissa Kantor
This Lullaby by Sarah Dessen
Mates, Dates and Inflatable Bras (series) by Cathy Hopkins
My Saucy Stuffed Ravioli by Cherry Whytock
Pretty Little Devils by Nancy Holder
Princess and the Pauper by Kate Brian
Princess Diaries by Meg Cabot (or anything by Meg Cabot)
TTYL by Lauren Myracle
Violet & Claire by Francesca Lia Block
What My Mother Doesn’t Know by Sonya Sones