Empress of the World, by Sara Ryan. I'm pretty sure it was her first novel, but it was amazing. It told the story of a girl attending an archeology program away from home for eight weeks, and while there seemingly discovering the truth about herself, making good friends for what seemed like the first time in her life, falling in love for the first time, etc. All that cliched teen stuff, given a new twist and brought together in a wonderful novel.
There were belivable characters, and interesting plot line, and a great writing style to back it all up. I'm warning you, though, it did deal with the main character discovering her bisexuality/homosexuality (you never find out completely for sure which it is), and while there is nothing graphic, some individuals may find it objectional (homophobes in particular), or undesirable to read about.