Caddycruiser makes some good points, almost all of which, IMHO, are accurate.The press liked the Intrigue because it straddled the middle ground between the then Regal and the still with us Grand Prix...meaning it hit the "sweet spot" in balancing nimble, athletic handling and a supple, controlled ride. I absolutely loved the ones I've rented for achieving that balance.
You are right. Going into the LaCrosse is very Buick. The 3800 is a tad quieter than it has been in the past, but not to the extent that they rave about. Perhaps it is the 3.6 that gets you that level of quiet. I only know 400 miles of driving a 3800 equipped LaCrosse. I will say that the feel at idle is improved. As far as handling goes, the LaCrosse is, again, still a Buick. There is some ponderous wallowing over highway undulations and some body lean if pushed too hard. This would be the case when the suspension is in CX and CXL form.
The Grand Prix is an adult's go kart. It's a fun car to drive and inspires more confidence when pushed harder. However, the Intrigue does not approach that level of sportiness as Caddycruiser indicates, though it comes damn close. The Intrigue still retains a little bit more Oldsmobile in its personality than leaning all the way over on the continuum to being Pontiac-like.
That's what sold the Intrigue and reeled in different consumers. A sporty sedan with great road manners combined with a luxurious enough driving experience, all for a very reasonable price. I wish the LaCrosse could be more like the Intrigue. Maybe "Ninety Eight Regency" was right, if I recall a post of his doubting the ability of the LaCrosse to step in as a "surrogate" Intrigue (on the old board).