I'd initially thought of getting a bigger bike for two upping with my son, but the cost of insurance on larger cc bikes for new riders and the doubling up of insurance when you own two bikes (though you can only ride one at a time) has put that on hold. In the meantime, perhaps some storage on the Ninja would make it a bit more useful as a tourer.
Givi is pretty detailed in how to apply its luggage to my particular Ninja. I went to them first to figure out what the hell the difference between monolock and monokey luggage is. Basically, Givi monokey is the heavy duty kit and monolock is the light duty system. Monokey can be switched between top and pannier duty as well as being built heavier and tougher. Monolock is topcase only and meant for smaller bikes doing lighter duty. Think monokey for a big touring bike with lots of luggage and monolock for sports bikes, smaller bikes and scooters.
Givi suggestions for a Ninja 650r '05-'08:
What I need for the Ninja Topbox:
Not bad for turning the Ninja into a two up tourer and long distance traveller. I see some Givi luggage coming from A Viscous Cycle in the near future.