How can I politely decline an expensive trip?

I don't think there's anything wrong with telling her you'd prefer a different destination. She most likely is offering France again because you told her it was so wonderful. Her goal is to make you happy and would love nothing more than to hear exactly what you prefer. I take my grown kids on trips from time to time and love to hear their preferences and not have to guess or wonder whether they will enjoy something or not. What about Italy? Thats great too. Have a great time where ever you end up :)