First, I would not waste whole layers for supplies, unless perhaps when they are unusually high current. With a good ground plane and good local bypassing, there is little purpose to power planes.
Second, I would use a single ground plane unless you are doing something unusual. If you want a capacitive shield, then you can dedicate the bottom layer to that, but it would be connected to ground at only one point near the middle of the board.
You can probably do your design with six layers. One of the two inner-most layers would be the ground plane, and then signals and power mixed everywhere else. I'd start with layer 3 being ground, layer 1 being the primary signal layer and layer 6 right behind it. I'd try to route as much of the power as possible in layer 4. Layers 2 and 5 are then left over for the router to use as it needs to make things work, although I'd set their costs higher so they only get used when needed.