Lots of great ideas in this thread. Keeping your gear off the floor if you have a basement, great advice. I even had my pedalboards on bricks. So many ways to have water in a basement, leaky water heater, busted pipe, rain water, etc.
I also have a cab for each of my amps, so I don't have an amp switcher, but do have a switching system (bunch of ABy boxes) for my amp inputs. Allows me to use my pedalboard into any amp I want to with just a few clips. On the ones with loops its a bit more tricky but doable.
I still have cinder block walls, so I did add some insulation, but I don't hang my guitars there. Also, monitor your humidity in the basement, you don't want it too high or too low for that matter, but too high is more the concern in a basement, though I have seen my basement under 40% RH in the dead of the winter.