David- even the W124 cars have some sort of gunk-sealant in the tailight and bumper areas. On the W124 cars, it is yellow in color.
In order to get away from the "tinny" sounding door, go to your nearest mobile hi-fi car stereo place and purchase a nice big piece of DynoMat (Crutchfield.com also has them).
Remove the door panel and moisture barrier, and place this in various *clean* surfaces of the door.
Your door will now have that nice "thunk" sound, and if you have speakers in the door, they won't rattle when played at loudly.
The only problem is, you'll probably want to do all doors, the trunk (esp. if you have a subwoofer in there), quarter panels, etc. This stuff really keeps sheet-metal from being resonant, and I like the fact that I'm not spraying it everywhere.
Best of luck,
PS: since you're in Newport Beach, please visit Bruce Strauss Autocare in Costa Mesa. Talk to Ralph or Julien in the Body Shop. They are very helpful.