I wouldnt recommend stepping the voltage up that much. The higher you put the voltage, the more energy your voltage regulator is going to be wasting. The 5v Vreg takes in the voltage, takes 5v and puts that out through the regulated pin, takes ~1v for itself to operate, and then anything thats left over is dissipated as heat. If you double the voltage, your going to be dissipating 6-8 volts(The 6v battery pack at full charge is more like 7v) as heat. Thats gunna get HOT! Also, look at the datasheets for your MCU and the sensors and make sure that the sensors arnt too powerful for your MCU. If the sensor is ouputting too much power or the wrong kind of signal, youll either fry your MCU or it just wont be able to talk to it.
A fix to the Vreg problem would be to get a 5v switching regulator. They basically turn the input line on and off repeatedly to give a 5v duty cycle and then smooth it out. I actually have 2 switching regulators in my supply that I think can take a max of 30vdc and they output 5v regulated and theres almost no energy waste! No or low energy waste is good so that your batteries will last longer
Although these ones are a little more than I need I think. they have like 5 or 6 pins rather than 3.... I havnt actually used them yet....
Hope this helped!