As someone who has seen alot of both cars stay away from the caddy.The northstar have a terrible oil leak problem(motor has to be removed and dissambled for repair).Not to mention they are terribly hard and expensive to work on(starter is located internally in the valley between the heads bout 5hr job).The rest of the car is just as stupidly coplicated and expensive.On a purly astecic point the caddy wins hands down

The buick has probally the most reliable motor and trans of any american car made.3.8 is also very easy and cheap to repair not to mention it is quite powerfull and efficient.All acc in the car are very straight forward and reliable as well

Which ever way you decide to go make a good inrormed purchase
good luck and enjoy whichever one it migh be

Just my.02
James