Tires

At about 50k I put new Yokohama tires on my wifes 2002 Century. When I first drove the car with the new tires it felt strange. I even thought it was pulling to the left. Took it back and they swapped front tires left to right etc.
Still felt strange. Well after I got used to them they ride and handle great. Now I find my wifes Century rides quieter and smoother than my 2003 Lasabre with the General tires on it. The Century also had Generals on it before.
Is this all in my head or can there be that much difference in one brand to another?

Not in your head at all... There can, and IS, that much difference between brands of tires. Even differences between makes within that brand, like a Sears version compared to the actual brand versions.

My Mom took BR goodrich Radial TA's off her 2000 Alero, and put on same size BF goodrich Traction TA's... and there was a big difference in ride and noise

Tires are probably one of the biggest handling factors you have easy control of for ride, comfort, noise, and handling! That is assuming that your alignment is correct and that none of your steering or suspension components are loose, damaged, or badly worn.

Recently for my Buick Century, I choose to spend $35 per tire buying top shelf "slightly" used tires rather than going with new $39 sale tires from a local discounter. Of course you need to select them carefully.

I have found that a good pair of tires and quality air shocks can make even a Chevette handle well (or at least a whole lot better, grin). I don't bother with the struts unless they are bad. My Century has struts in front and shocks in back.

The softest road ride I ever had was with my old 1994 Jeep when I aired down the tires to 15 pounds and then drove on roads to the gas station after 4 wheeling because my cheap compressor was too slow with large tires. Of course cornering would have been terrible because of the low pressure, and tire overheating would be a concern if I drove very far.