328i xDrive is a very competent package even in its "basic" form, and even without the sport suspension it will corner better than anything mainstream.
From then on, you have to decide whether the law of diminishing returns applies to you or not.
The sport suspension improves the handling, no doubt about it. But with my bad back, it's more of a pain (pun intended) to me than added value. It might put a smile on your face and be totally worth it for you. You decide.
Additionally, the standard 16" run flats are $350 a pop (dealer prices), while the 17" that come with the premium package are $520 a pop. Quite a difference for just 1 inch, eh? So when you are looking at a higher trim level, it is important to factor in the additional costs.
I got mine with a stick. It was very stiff for the first ~1,500km during break-in. Now it's getting smoother and smoother and is a joy to row. I know it's not an option for you. But not every upgrade adds value. You have to decide for yourself.
As for 2008 used for $30,000 vs 2011 new for $42,000, I would go for a new one, no doubt. With a 2008 model year, you will probably get a 4-year old car (quite possibly manufactured in 2007) for 71% of the price of a new one. It does look nicer with the two-tone interior but it's not the main reason why you buy a BWM in the first place. My interior is all black, and I went through the same thought process you did, and after a month of driving I don't care about this little detail anymore. And once you get personally "attached" to "your" car, neither will you.
The standard seats provide plenty of lateral support, the letherette interior is very durable, looks nice, so I don't care that it's not real lether.
I don't have the bluetooth or heated steering wheel, but I still have the BMW chassis, the sweet I6 engine, xDrive for the winter, dual climate control and heated seats and mirrors. That's all I need or want. Your mileage may vary.