*The lower the humidity the more the proof will rise (alcohol evaporates at constant rate, water evaporates faster when dry).
*The more severe the temp fluctuation the more (and faster) barrel influence you will get. The higher you go, the more flux.
Based on those factors, I would want my younger bourbon from the higher floors, but my older bourbon from the lower. At a younger age, you would get more "barrel influence" faster at the higher floors. But an older bourbon might get thrown out of balance if it stays at higher floors longer.
The issue of oxidation is also important, but is (somewhat) distinct from barrel influence. The less booze in the barrel, the faster the oxidation. And obviously the longer it sits, the more oxidation. Oxidation at first opens up a whiskey and accents the characteristics of a bourbon (i.e. the spice, fruit, etc.), but too much oxidation and it becomes flat, muted and a bit metallic.