I would stick with Buick if I were you. I like the fact that you traded a Toyota for your LeSabre. It is unfortunate you have not had better reliability with such low miles. LeSabres are generally reliable cars. I personally love the Park Avenue. I currently have a '99 and plan to trade it in the next year for one of the last '05's. I don't care for the look of the Lucerne, but the new Enclave is quite a looker if you can afford the initial price not to mention the gas bills.
I owned two Cadillac Deville's and had nightmare results when it came to repairs on them. Every bit as bad as what is described on the Buick, maybe worse. I was very disappointed that GM's top of the line car was not any more reliable.
I also I have an 01 LeSabre, and so far I have had the same problems with my wheel bearings, and also my tie rod and rotors, plus my car now has started to just die out on me; the radio and everything else will work, but I will have no power steering or brakes. I can't find out what's wrong with it.
The quality certainly was lacking in many of the 2000 and up Buick Lesabres. I had two prior to buying my 2001 brand new. I had to have the fuel pressure regulator replaced at 9,000 miles, all four wheel covers replaced under warranty (paint peeled off) and numerous other problems under warranty. The topper was when there was a recall for coolant problems, which GM "fixed" by adding bar's stop leak, resulting in a warped head 2 months later. GM would not repair, fortunately dealer repaired at no cost to me. Gas gauge doesn't work, window repaired. No more Buicks or any GM's for me.
I'm surprised at some of these comments. We sold our 32-year-old LeSabre last year in perfect condition with over 277,000 miles. It had never had a single repair except for 3 brake pad replacements. Our current GM vehicle has over 80,000 miles and has not even had a brake job (or anything else) yet. We're sold on Ford and GM, and have never had any problems with either manufacturer's products.
Cadillac is good, but Buick is more reliable. The luxury market is generally far less reliable than the upscale market as a whole -- more advanced components and more room for error, and parts cost more.
The good thing about Cadillac, is that if you buy a used one, you can usually find people who take really good care of them. Buy an older used one that's like a brand new car, and don't pay too much.
To be honest, you probably won't buy a car more reliable than a Buick. It sounds like yours probably rusted out over the years, and your mechanics are overcharging you, which is not Buick or GM's fault, but the manner the car has been maintained over the years.
On the other hand, I wouldn't buy a Chevrolet, and I'd be wary of a lot of Pontiacs too -- the 3.4L engine sucked, where the 3.8L was great.