I have 10 positions, which is why drop bars are so much more comfortable for long rides than flat bars. I also think "classic" curve type bars with long flats in the drops are more adaptable to finding comfort in the drops (4,5,7 below) Roughly in order of % usage:

1 Just above the hoods so heels of hands are on bar tape, first two fingers or so are on hoods
2 On the hoods
3 On the tops, right where they curve forward and down
4 Heels of hands on flat part of drops, first couple of fingers on the curve, finger ends touching levers
5 At the very ends of the drops
6 On the tops near the stem - mostly easy pedaling/resting or climbing
7 Whole hands on the curve of the drops, most aero position, with fingers on levers.
8 On the knobs at the front of the hoods (where the levers come out)
9 Same as 8 except leaning down enough for forearms to rest on bars near downcurve
10 Forearms on tops near stem, hands extending out and clasped fake time trial position (very seldom!)