I have a 2007 Azera. It has never, apparently, had as bad a set of ride quality issues as some of the earlier year models, but it still bugged me. In stock form it liked to float sometimes over "sine-waves" (e.g., large and lengthy frost heaves and the like), and it shook your fillings in your teeth over tar strips and smallish cracks.
I have found a partial solution some othes may be interested in. First I replaced the OEM tires with Bridgestone Serenity tires. The noise (never really bad to begin with) decreased a bit, and the ride became a bit better. But the improvement was pretty marginal.
Then, just this spring (of 2012) I found that Monroe had just started making shocks and struts specifically to solve some of the types of complaints I've mentioned above. The part number was 905983. Sorry, I don't remember if that's the front or the back. But it should allow your parts store to figure out the new series Monroe has recently begun to offer ("so high-performance European cars will better suits the tastes and needs of some American cars" -- quote from Monroe literature.
Installing these Monroes made quite a substantial improvement in nearly every way. From what I've read on the web for a couple of years, I'm guessing this is the best improvement you can expect in ride quality cf any other aftermarket parts.
The slow and mid-speed ride improved a lot. Even my wife spontaneously commented on it (and she's not usually tuned in much to these things). The roughness over small imperfections is much(!) improved. And the ride on the highway generally quite a bit better, but with a proviso. Strangely, when you hit about 75 mph, the improvements in all areas seem to largely disappear. At least some(!) of the float comes back, but not as much as the original. The ride gets pretty choppy again over rough pavement -- not much better than in the very beginning -- (but is simply great on smooth pavement).
The only downside is once the heat here in Texas went over 100 this summer, the dampers developed some noise (thumps, squeaks, and the like) over pavement, but only at VERY low speed. 5 mph or less, basically. And it gets worse the higher the temp, or the harder the car is driven. But, again, only at very low speed is there a "problem" at all to begin with. However, when I bought the shocks and struts from an online dealer they were supposed to send new mounts all the way around to go with the new dampers. However, they only sent one of each. I had to go on a long trip in a couple of days, so just used the original four mounts because I didn't have time to wait for new ones from Monroe. So ... it might be that if I had been able to replace the mounts with the Monroe parts even this small problem might not exist. In just the past couple of days the temps have dropped back to about 90 and the noise has almost disappeared. So I'm hopeful that at reasonable temperatures it goes away all together again.
All in all, the Monroe's gave the car a better ride -- one more in keeping with a near-luxury type vehicle. After 4 years, I'm finally (personally) satisfied with my "reengineering" of the ride. ("Your results -- and tastes -- may vary!).
Hope all this info helps someone else.