I use a two or three z-level tall hallway with 3x3 rooms on each side, with double wide walls between the tomb chambers so each has its own engraving. I only dig out a few at a time, but a hall long enough for four rooms on a side gives either 16 or 24 burial locations due to the multiple levels.
Z-level +0 Z-level +1 Z-level +2
.....XXXXXXXXXX .....XXXXXXXXXX .....XXXXXXXXXX
.....X+++XX+++X .....X+++XX+++X .....X+++XX+++X
.....X+++XX+++X .....X+++XX+++X .....X+++XX+++X
.....X+++XX+++X .....X+++XX+++X .....X+++XX+++X
.....XXDXXXXDXX XXXXXXXDXXXXDXX XXXXXXXDXXXXDXX
....XX+++++++++ X+^X+++++++++++ X_v++++++++++++
....X^+++++++++ D++++v_________ X______________
....X^+++++++++ D++++v_________ X______________
....XX+++++++++ X+^X+++++++++++ X_v++++++++++++
.....XXDXXXXDXX XXXXXXXDXXXXDXX XXXXXXXDXXXXDXX
.....X+++XX+++X .....X+++XX+++X .....X+++XX+++X
.....X+++XX+++X .....X+++XX+++X .....X+++XX+++X
.....X+++XX+++X .....X+++XX+++X .....X+++XX+++X
.....XXXXXXXXXX .....XXXXXXXXXX .....XXXXXXXXXX
X wall, . hidden area, _ channel, + floor, ^ ramp up, D door, v ramp down
This is three levels, entrance in the middle, with ramps up and down to the other two. All levels have the chambers one on top of the other, but that can be varied depending on space and preference.