New, (thicker) door weather stripping will certainly help your door rattles. Put stuff in that has to compress 1/2 the thickness when the door is closed. I use 2 or 3 different types depending on where it's used on the door and how much of a gap I need to fill (CMC body - I live for door gaps).
The last resort is a new rubber bumper on the door latch striker (the part on the body) if it's worn. I have no idea where you can get those (Bug City?) but they are replaceable.