Almost all of Meg Cabot's books are like that.
Light and girly but with a kick-ass female character.
I know a lot of people like the Mediator series.
You should also read the Princess Diaries books.
They are soooo much better than the movies.
If you liked 1-800-where-are-u, you've probobly already read these, but just in case.
If you have read all her books, there's this really good british series called Confessions of Georgia Nicolson.
The books are sort of crappy, but their light and hilariously funny.
The first is called Angus, Thongs and Full-Frontal Snogging.
lol
~Cheers~