I'm one of those odd folk who can't really give monkeys what the car looks like, but I was sold on the CLS as it just works so well. The fact that it is based on E class underpinnings sells the car short. The shell is much stiffer and the centre of gravity lower so feels completly different to drive. Sporting, but comfortable. Buy the car right and it is not a finacial disaster either and is just so much better than the some of it's parts.
Can't help with the third vehicle senario, I gave my wife the choice of the CLS or ML when the S went, and she really likes the ML so we use that when the dogs are with us. I just picked up my new 'third' vehicle on Saturday and my wife won't get on it! What's wrong with 0-60 in 2.7 secs?