Eva,
I too am a small town (pop 1400 on Monday) person, so I empathize with some of what you are going through. I just last week bought a nice certified 2008 DTS with 70Kmi from the dealer 70 miles away for $15K. Because of experiences friends have had and because this purchase will leave me with less disposable income I decided to add on the additional four year bumper to bumper warranty that tacked another couple thousand to the price, but on these cars it doesn't take too many service calls to eat that up.
The dealer here is Rydell Chevrolet/Cadillac and has one of the best service centers I have ever seen. This was one of the reasons I bought from them. If you happen to be near North Dakota I would be happy to take a personal preliminary look at any of their DTS's for you. They are a non-dickering window price dealership which I sort of like.
Good luck on your hunt!