I usually book g-b. On occasion I take an upgrade to A, or PH, but only if it's a good deal. I usually start out as low as I can, except for the R ships, which I go to at least an Oceanview.
But I'm always willing to share to get an earlier time, or not be rigid on which day I eat where. If I have to I'll eat in Specialties back to back, although we prefer to spread them out through the trip. Obviously your mileage varies.