2000s YA romance about a nanny/au pair

I just had a memory of a book I really enjoyed as a kid, about 15 years ago, but I can't remember the title at all. It was about a girl in America who became a nanny/au pair for a family she ended up hating. She ran away with their mistreated iguana and ended up working in some kind of holiday resort, I think, where some kind of romance and drama ensued. I can't remember much else. Any ideas?