I just bought a Kool Stop tire jack. I can see that it can make the initial tire mounting a lot more smooth and involving very few curse words. My wife will appreciate that. I have some rims that are notoriously difficult to mount fresh tires on.

Once any tire has been on the rim a while it is easy to mount with just your hands. I can't see any reason to bring the Kool Stop tire jack along on a ride unless you are worried about a flat on a brand new tire.