I've decided that the network of caves that leads to her home is her favourite place to drive on. Part of the reason she isn't home much is to experience a variety of roads, but when she gets home sick, the caves tend to give her a nostalgic calm even before she makes it home. Plus, it's an enclosed area, so there's less risk involved when she gains speed. As for actual roads, she'll tire of any pass that she's been on for too often, so there's not really a preference. Remember, she's really fast, so there's a lot of road that she's had the opportunity to drive on, and I (personally) find that routes are more fun when you drive them for the first time.