Nobody gets a tomb when I'm in charge. Corpses are incremental lag at best and zombies waiting to happen at worst, so cremation is mandatory. You get a magma bath and a slab, enjoy. Damn your needs, we have a dining hall that is just that good. Where your slab goes when you die depends on what you did in life. A soldier's slab goes in the barracks, a broker's slab goes near the trade depot, so on and so forth. wherever it ends up, it gets nestled into an alcove which is then sealed with a fortification to protect from harm while allowing safe viewing.
I'm a little less spartan when I play humans, so I try to make an above-ground graveyard like real life. Key word being try. When I can, I fence off an area with fortifications and channel rows of 1x1 holes in the ground. Coffin goes in hole, person goes in coffin, floor tile goes on top of hole. Rinse and repeat until I run out of room, in which case I build an access mausoleum, dig down, and entomb like you normally would. The aesthetics of it barely justify the time and amount of space it takes, and there's a lot of room for something to go wrong, so I don't recommend it as a staple feature for fortress play.
But the best part is that I play with modded necromancers who get [EXTRAVISION] in exchange for weaker zombies. This means they can raise the dead through walls as long as they can get close enough. Combine that with an above-ground, easy to reach corpse supply and you get some HILARIOUS scenarios.