Low current battery monitoring
The voltage divider needs to join the MCU in deep-sleep mode then... This can be achieved with a P channel FET (for instance).... When the MCU wakes up, it will want to measure the battery voltage so what it can do is turn on a circuit formed around a P channel FET that connects the battery +V to the voltage divider: -



The ADC input is shown to the right and there will be no voltage reaching it unless the MCU has activated the BC547 via the 10k resistor. Without activation, the P channel FET is turned off and virtually open circuit. If you can program the MCU to have a pull-down on its control pin when asleep that should be it, else add another (say) 10k resistor from that point to ground - this ensures the P channel FET is completely off.

A small word of warning, choose a P channel fet with low leakage current when off else there will be a slight drain on battery life but most fets are going to be under 100nA and many in the region of 1nA.

One final thing - how does the voltage regulator perform on it's standby current when the micro is off - do you need to take care of it as well?