We are planning a kitchen remodel in our 1975 tract house which has a drop ceiling in the kitchen (drops 7.25"). We have cut away the drywall on the sides of the recessed florescent light in the center of the kitchen, which has allowed us to peek at what is hidden in the ceiling. We can't see everything clearly this way, but we don't want to cut more drywall until we know that we can raise the ceiling.
Above the kitchen is the kids bath (with one sink, toilet and bathtub) and the master BR (with shower, toilet and 2 sinks). Most of the waste lines for these bathrooms are below the joists, in the drop part of the ceiling. We are looking for help in re-routing these waste lines with the ultimate goal of raising the ceiling all the way to the joists. If this isn't achievable, we would still like to raise the ceiling as much as possible and add soffits above the cabinets if necessary.
I have made a crude drawing of the ceiling with approximate locations of the waste lines and heating/venting ducts. The ONLY waste line that is above the bottom of the joists is the one that is cross-hatched. All of the heating/venting ducts are above the bottom of the joists. There are also supply lines running perpendicular to the joists, hanging just below the bottom of the joists - we aren't too worried about re-routing these. We can't see very well in the upper left corner (where most of the pipes are, of course ):
the thick grey lines are walls
the skinny yellow lines are joists
the square in the middle is the 4'x4' recessed florescent fixture
the green lines are the waste lines
the solid black circles are vertical junctions
the open black circles are the main stacks
the fixtures are in the bathrooms upstairs