I'll give you reasons that I would consider a full fluid exchange after pan & filter.
1) Most people do not have their transmissions serviced at all. If this was the case with your van then you have transmission fluid with 118,000 miles on it. After a pan/filter service you will still have about 50-60% of your fluid with 118,000 miles on it.
2) Another thing that sometimes happens is that people do have their fluid changed by general purpose shops. Many of those will use general purpose transmission fluids that they combine with some "additive" that is supposed to make the fluid into ATF+4 compatible fluid. Its not.
If this was my van purchased at 96,000 miles I would be looking to have a trouble free trip to 200,000 miles. The thing that will most likely interfere with that on these vehicles is transmission trouble. I hate uncertainty about maintenance and would want to wipe the slate clean and start fresh knowing that I had a new filter and a verified 99% genuine, clean, fresh ATF+4 fluid.
After this wiping of the slate, then I would go to pan/filter only every 30K or so.