the coolant hoses dont seem to brake on these cars like they did on older cars. I would replace everything else. On these cars they have issues with the coolant elbow and coolant leaks on the lower intake manifold gaskets. I'm guessing you purchased a 180* t-stat?
If you have a leak replace the coolant hose, if no leak keep driving, I've had 6 3800 cars now and never once had problems with the coolant hoses, I have had more problems with coolant leaking internally becuase of failed intake manifold gaskets. If you want to insure long life of the motor return everything and put in new aluminum framed intake gaskets and DO NOT use dexcool.
No real reason to thow parts at it though unless we have indenfied a problem, I have over 150,000 miles on my 2000 SSEi and no problems with the intake gaskets yet and theyve never been replaced.