From the time I bought it a few months ago, I noticed a high level of road noise coming through the passenger side doors. Driver's side is fine.
I checked the rubber seals around the door and they are fine. Then I noticed the small gap between the door and the body.

When the passenger side doors are closed (both front and rear) there is around a 1/4 inch gap between the top edge of the rubber door seal (not exactly sure what this is called) and the car body. The close up pics below illustrate this pretty well. In fact, you can see some rust patches starting -- no doubt from the rain water that has seeped in.

Car has a rebuilt title -- it was involved in a passenger side collision about 5 years ago.

Obviously the doors need to be adjusted so there is no more gap when closed. Is this an easy thing I can do myself (somehow) or will I need to take it in to a mechanic or body shop? Any and all advice on this is welcome!

 

The door is obviously not lined up properly. Now is the problem with the door or was the body messed up in the accident? It will be tough to tell from the pictures.

I would guess that rust is from the passenger doors hitting the pillar and not simply from water getting in there. In the one picture, it looks like you have rust where the rear passenger door meets up with the body, but it is hard to tell.

Go to the common DIY thread on top of the gen tech help forum. There is a link in there for online shop manuals. The 94 shop manual is almost identical to your 97. On page 20-16, it shows how to adjust the hinge. This is for a coupe, but should work for the sedan. This adjustment may be enough for you to get the door to seal properly.