Well then the answer is simple, the best case solution is a switch mode 5 volt to 3.3volt regulator. It will not waste 5 volt power just to turn it into heat, so the total wattage consumed from the 5 volt bus from any given 3.3 volt load will be less. Next question?
The noise from the switcher isn't an issue for digital designs and easily dealt with for 10 bit A/D conversion with a 5 V reference because even the fastest A/D conversion I did averaged several measurements for accuracy and external noise rejection.
In bread boarding I've found that those little breadboard jumpers are totally unsuitable for carrying any current above 100 mA or so, depending... As they are 30 Ga stranded and with the combination of jumpers and breadboard connections typical are lossy. I start with 5 V from an external PSU and after 6" of travel through jumpers and pins the voltage ends @ 4.5 to 4.75 V.