See what you think after you drive one. We considered an A4 for a cheapie beater but after a test drive my wife and I both said "no thanks, S4 or nothing". Yeah, those 540 wagons are nice, but I hear they sometimes have expensive issues so I always figure that, well, there's probably a good reason why the owner isn't keeping it
That's often true about a *lot* of cool cars...sigh..
I think I'd wait and see what you end up getting your wife.