You can't go wrong with an '08 335i Coupe. I love the handling on BMWs. It's very sporty and pretty luxurious. The technology behind the car is awesome, too. I'm saving up for one right now
The 335i is basically the benchmark that all luxury car companies compare when they're making a luxury sport coupe.
Another good one would be a Mercedes C-class. They're great, but not as sporty as BMW. Nor do they handle as well. Their ride is buttery smooth, though. They've got a better nav system, too.
You can't go wrong with Lexus, either. They're uber luxurious, but lacking the sportiness. If you get something from Lexus, look at an IS, GS, or LS.
Infiniti makes some great cars, but they're a little on the cheap side. And when I mean cheap, I mean like some cheap material. The G37 is an excellent car and is made to compete with the 335i. Its ride is a bit smoother, but it's lacking that quality feeling.
Audi's always great, but they are a little slow unless you get the S versions. The new A4 looks pretty cool. They are smooth and comfortable, but they're not as fun to drive as a BMW or Merecedes. Also, I find them kinda boxy.