Best order for PCB power planes?
This set of articles has been referenced a number of times on this site and it's quite a good primer. Read through it and decide which goals you are content to optimize for.

http://www.hottconsultants.com/techtips/pcb-stack-up-1.html
http://www.hottconsultants.com/techtips/pcb-stack-up-2.html
http://www.hottconsultants.com/techtips/pcb-stack-up-3.html

... read on for more layers.

Here is an excerpt of the objectives of stackup design:


  When using multi-layer boards there are five objectives that you
  should try to achieve.  They are:
  
  
  A signal layer should always be adjacent to a plane. 
  Signal layers should be tightly coupled (close) to their adjacent planes. 
  Power and Ground planes should be closely coupled together. 
  High-speed signals should be routed on buried layers located between planes.  In this way the planes can act as shields and contain
  the radiation from the high-speed traces. 
  Multiple ground planes are very advantageous, since they will lower the ground (reference plane) impedance of the board and reduce the
  common-mode radiation..
  


If you read through the articles, you'll find that there is no one "best" way to stack up your design. There are just a number of possibilities with different characteristics and tradeoffs.