The cabins of the DC-9/MD-80/MD-90 and 717 aircraft are similar but there are a couple of major differences.
The DC-9 and 717 have one galley in the front and two lavatories at the rear. The MD-80 & MD-90 have two galleys, front and rear as shown in the seat map to the right. The rear galley is 3 rows up from the back and there is a door, which you can see in the illustration above.
The seating configuration is either 2×3 or 3×2 (MD-88 shown in the illustration). EXCEPTION: the MD-87 only is configured like a DC9 except that the row over the wing where the exit is only has one seat on the left and two on the right.
In all of these aircraft, the last three rows will not have a window view because it is blocked by the jet engine.