[BigAls87Z28]

Two very different cars, and two are totaly gunna be different.

CTS's level of refinement and quality will trump the Malibu's, even if the Malibu's is pretty good. Better handling and RWD gets you a sportier feel on the road then the Malibu, which has been tuned to ride like a family car should.
Both the LTZ and Base CTS are equiped with the same V6, only the CTS's makes more power, but both carry the 6spd auto which is cool.
The Malibu doesnt have features like navi or dual zone auto climate controls, but does come with some interesting features.

Worse case, if you cant decide, the G8 would split the middle. G8 has the CTS's handling, but lower price. CTS starts at 32k, but you cant find one unless you order one, for under 36k. G8 wont get navi, and I belive that not even XM is an option which has upset several people who expect it in a car like that, even if the Commodore has it in Oz.
GM has yet to get the handle down on importing vehicles and the options they should have.

Malibu would be a hell of a buy, and probably give you tons of years of service and it looks STUNNING in real life, but if you want something more with sporty handling and more room Id go G8. If you wanted all that, and luxury thats tops int he world, the CTS is a heck of a ride. If you go CTS, keep an eye on them options...car gets price fast.
Loaded CTS AWD with the FE3 suspension 6spd manual with performanace W rated Mich Pilot Sport 2's can top out at near 50k.