Ideal % jump between gears? I am wondering if people prefer equally spaced gears (such as 20% per gear change) or if (like on motorcycles), the lower gears are spread out more and the upper gears are "tighter" (more closely spaced as far as ratios).  From my limited bicycle riding experience, other than the super low granny gear ratio, I like to have the lower gears spread out so the shifts are not instantaneous, and have the higher gears closer so for example, if you are chugging along at a good pace and encounter a slight headwind, you may not want to downshift and get about 20% more cadence.  Perhaps 10% will suffice.  Motorcycles generally have a spread of about 2.5 (street bikes) and some dual sport bikes are as wide as 3.  For bicycles, since we have very limited input power (generally about a few hundred watts max), it seems we need many more gears and much closer spaced to harness that little bit of power.
Ideal differences are generally thought of to be around 15%.  Changes in excess of 20% make it difficult to select a proper gear for spinning based on varied conditions.  Changes of less than 10% are so slight that they will almost unnoticeable to most unskilled riders and even some skilled riders.  

You make an assumptions about the purpose of gearing on a bicycle that is incorrect.  Gearing is present to provide the proper gear to maintain a near constant and comfortable for the rider cadence in a variety of changing conditions.  They are not simply there to provide a shifting mechanism until the bike "gets up to speed".  A combustion engine has a power range that is most efficient at a certain RPM, but there is no comfort level involved.  It will produce any amount of power in it's range given the proper amount of gas. The human body does not work in the same manner.  There is a very defined range that riders are comfortable producing power in.  Generally producing power above that range causes drastic losses overall and can only be maintained for so long.  You miss the point that lower gears also need to be closely spaced to maintain that output in conditions that greatly slow a bicycle (hills, wind, etc).