it's never a bad idea to coat the inside of the frame tubes with frame saver or WD-40, but considering that you keep your bikes in climate controlled spaces all the time, i wouldn't worry about going to those lengths.

frames can and do collect water, but mostly from being left in the rain and from being ridden without fenders. if you don't leave your bike out in the rain, and you have fenders, there's really little chance of water accumulating in your frame. many frames have drain/vent holes in the seat stays, fender stays, and fork blades, but what is often overlooked is the bottom bracket shell. if any water is to accumulate anywhere, that's usually the place. it's like a catch basin.

if you left your bike out in damp weather (like in a shed) or you rode in the rain often, i would do it. but since you don't do either, i really wouldn't bother.