I wouldn't count the <strong class='bbc'>S4[/b] out because of current resale value. All Audi S-Cars are low production and their value will always creep back up. Immediately off the lot, Audi's will depreciate, granted. But given the fact that there will be thousands of Bimmers out there for every S4, the S4 price will just get stronger. Also the geography matters a lot. Northern demand for Quattro is very high.
I had a similar situation with a relatively rare 9 year old Audi Coupe Quattro that I sold a year ago. New, the car was in the low $30's. I drove it for 9 years, placed an ad on the internet and literally had people bidding to get me to sell them the car for $20 grand. That's strong resale! At that time a comparably equipped 325is was selling for $12-13 tops.
Exclusivity is important to me. The BMW is an excellent car, I love them, but around my neighborhood they are as common as mini vans.
I looked seriously at the 328i before the S4 came out and liked it a lot. The base sticker on the S4 was higher but by the time I added all the options necessary on the 328i, the price was about the same. Quattro was the kicker. So I went with the S4. It was a close decision but I don't regret it.
As far as the old M3s vs the new 330i, send an email to DavidB. He just replaced his '95 (I think) M3 with a new 330i and I believe he counts the new 330i better on all counts, handling, convenience, etc.
I just love the "hunt" for a new car!