With some professional ap's, they have built in autoranging/autosensing abilities.
I don't think typical devices have that autosensing ability. However what you could do (i'd imagine) is find the max range, while keeping at the highest connection speed from your ap, and place your other two stations at that those spots on opposite sides of the main ap (maybe while downloading a movie or other large file). So your ap2 and ap3 would act as repeaters, assuming you aren't going to run that cat 5e to them. If you can run the lines out to them, i'd say move out to around 130% of the max range (or less) of the main ap. That way you still get some overlapping while maxing the range width.
At work, i can walk from one end of the building to the other without losing my connection, or reconnecting to a different ap it's all automatic. However, i don't know that your laptop or wireless device will automatically switch as you move in to another ap zone. Someone more proficient in wireless technologies can hopefully answer as to that.
With all that said...You could stack 15 or so wireless devices on top of each other if you wanted, so long as they had the capibility of running at different frequencies (which most do).