With the Jetta and the Audi you're talking about a $20,000 car vs a $35,000 car, its like comparing a Corolla to an IS300, theres no comparison to be made. As for the interiors, I can see the family resemblence but thats it, and you truly are the only person I've ever heard say anything bad about an Audi interior. Even Lexus takes design cues in their interiors from Audi.
Audis are very under-appreciated cars. The A8 is a fantastic car, very cutting edge, the A6 is a great mid road luxury car with a good ride, great interior, good power and economy. The A4 is a little small for me, but I see it as a worthy competitor to the 3 series BMW.
Thing about the A4 is that its not designed to compete against the GS300, its designed to compete against the 3 series, C class, IS300.
My only qualm with Volkswagen is the quality issues that my mother faced with her car and the way they dealt with them, it would definately keep me from ever buying a VW, and will probably keep me from buying an Audi.