It does very much depend on the child and his or her interests and parents know them best. However, we would say children as young as 4 get something from a tour, and everyone whatever age, loves seeing the paper machine in action. The machine room can be the noisiest spot, if you are bringing a person who dislikes loud noise. You are welcome to bring ear defenders.
There is lots of information on a tour, but tour guides adapt to the audience they have. Often talking at different levels to different individuals. We try to ensure it is interesting for all.
There are items that will appeal to a younger audience as well as a paper scientist.
In school holidays we lay on paper crafting activities and special themed boat trips. A boat ride is always popular with the children!