Jane Gardam's Bilgewater is an absolute gem of a coming of age book. For someone who might be a bit of a reluctant reader, it's short and not overtly literary, but has lots of depth.
Does she enjoy romance?
Jennifer Crusie is very funny - light, but not throwaway. There's sex, but good, fun sex, which is something 16 year olds should know exists.
Heather Morgan and Jessica Cocks books, Messy, Spolied and The Royal We, are smart, funny YA books with strong, but flawed female characters.
Messy starts with a teenager losing her mother and discovering her father is very famous. The insider stuff about Hollywood is laugh out loud funny.
The Royal We is a totally unbelievable novel about a young American woman who meets, and falls in love with an English prince. I know, could never happen. (Published several years ago). A really fun read.