I have a 99 villager van with 100k miles. It has been a very good van.I have been told that the ride would improve if new shocks and struts were installed. the original ones are on the van. I also have been told that you get used to the poorer ride over time. I bounced the van in the drive way and it stops immediately, doesnt keep on bouncing. Will changing them out make a noticible difference?

Yes it will. That is a general test you did. The real test is when your going down the road and have slam on the brakes and the nose dives. Another road test is a bump test. The van goes around a u-turn exit that is bumpy and you feel it losing traction over the bumps. The final test is that if you have more than 60k miles on them they can be changed regardless of what type of use you have given the can. Shocks/struts have seals that just wear out from the fluide that they store inside. The older the seal the weaker the strut/shock. If you have no other problems and you have the money and plan on keep it for another 50k or so change them.