Paolino:
Tu gia' lo sai quale macchina io ti consigliero di comprare: la LaCrosse!
Seriously, first and foremost, you need a car that will be super dependable given the fact that you watch your $ (or at least I think you do). There is nothing wrong with the 3800. In fact, there is everything right with it! Today, mine will turn over 225,000 miles and it still performs flawlessly. God, I love that damn car. If you are looking for a 10+ year car, this is a good the car for you! As for the height issue, how does that LaX feel? At 5'-10", this is never a concern for me. Isn't L.I. hot and humid in the summers? Do you really want a CXL with the leather? How about a CX with potentially nicer cloth that they may put in there next M.Y.? You can get the Comfort and Convenience package and put some money back in your wallet! Consumer Reports has already given this car a clean bill of health.
The Impala is nice. The mileage is great with the 3.5 Yes, 1 LT and 2 LT have the smaller engine and that's all you need. But, this is a modification of sorts and you should wait another model year to make sure VVT electronics are all worked out.
This may be a nice car for you if you need more space, but you're not even 30 yet, if I recall, so do you want an Impala? (Don't slap me, Scharmer 05!) How about a Monte Carlo without the tacky $h! on it? Or is that too Guido or "spazzatura bianca" for you? It is mechanically identical to the Impala with the same powertrain. Your choice.
The Aura is brand new. I never recommend a new car. I'm too cheap to be someone's guinea pig.
Yeah...yada yada...the Accord is a good car...but it feels SOOOO Japanese. It has also gotten uglier instead of better looking. Don't do it. Buy American.
When will you consummate this purchase? Buona fortuna!