I got rid of my 84 Buick Century about a year ago. I currently own an 86 Buick LeSabre. Both are examples of what was wrong with GM at the time. Not a problem with the basic platform of either car, but lots of detail issues, especially considering that Buick is supposed to be the near-luxury division. (Note: Neither car reflects my choices in vehicles, but rather my lack of desire to go into debt over cars. The LeSabre is the result of taking too long to make up my mind, and missing out on 3 different cars as my Sunbird faded into death)
The Century had a pushrod 4 cylinder engine. Fine in a Chevy, underpowered and unsophisticated for the Buick market. Should have been at least a OHC 4, and probably a V6 minimum. The LeSabre's engine is the 3800 V6. Ancient design, but continual development has resulted in a pretty decent engine. Adequate power and smoothness, not one of the problems with this car.
Both have the standard GM heat controls--Top lever controls whether the AC is on, whether or not fresh air is on, and where the air will blow from. Because it does everything in a limited number of positions, some choices are not available. Bottom lever mixes heated air with whatever you're doing. In the Buick class, the controls should be at least as good as an Escort or Sentra. One control should be for where the air goes. One control whether or not AC is on or off, one for whether or not fresh air is on or off. You can save full climate control for Cadillac, but for a near-luxury, some form of thermostat for the AC wouldn't be difficult, and would be a good way to differentiate.
Seats are another weak area on both Buicks. Neither had adjustment for the driver's seat back angle--That is a pretty minimal requirement, even on a bench seat. Materials are decent, and held up well enough for the age, assuming no repairs.
Instrument panel--The Century had reasonable gauges. The LeSabre has spedo, fuel, odometer and gear indicator, everything else is idiot lights. LeSabre's uninformative dash does announce "Information Center" on each side-Tacky, even more so because there is so little information. I suppose you can argue that an upscale driver doesn't want gauges--I can somewhat accept that, although I think this is an economy rather than a style decision. Buick should have a trip odometer standard. It should also have a stand-alone clock, not just a mode on the radio.
Cupholders and storage--LeSabre has a glovebox for it's sole interior storage. I don't remember if the Century had pockets in the doors, I think it did. Both should have cup holders, although I'll give them a break for their age--What seems obvious now might not have been then. Both should also have some other pockets and cubbies in the dash-Use the space taken up by "Information center" signs.
A Buick the size of the LeSabre should have power windows. It does have power door locks, but these are obviously tacked on. These should be integrated with the key locks, so you can unlock all doors at once with the key.
Everything except the AC thermostat is stuff I had on much cheaper cars of similar age.
This of course isn't an exhaustive list of GM's mistakes-I don't want to go into the mind that decided a V-8 Saab SUV is a good idea....