I'm also adamant about my fortress looking good; if I misdig a tile or two and make my waterfall entrance/dining room/whatever look awkward or accidentally hit an offshoot from the cave river in 23a, I flail about in frustration.
I usually just build walls to even-out the room. Although, I'm on the list for a succession game where one of the rules "no straight lines".... everything has to be 'organic'. It's going to push my OCD to its limits.
Somehow that is among the most horrifying things I've heard of in DF to date... a fortress whose insides are as twisted and madening as the minds of its inhabitants...
In my fortresses... let's see...
Native-born dwarves are treated as higher than nobility or legendaries, and are the only ones allowed to engrave. Farmis *always* include a greenhouse, which is *always* made with green glass. If possible, the entrance will be made into a sheer cliff with a chasm that needs a drawbridge over it, even if it means spending a season or two sculpting the mountain before I dig it; flat planes are alright, but eventually will require an above-ground constructed fort just to make the hole look nice. Symmetry caves to function in most of the fort- especially the farm areas, where the related industries are so complicated I have little mazes of connected rooms and stockyards- but tombs *must* be perfeclty symetrical, completely smoothed, with every dwarf getting at least a 2x2 room, pets getting an alcove, etc. No tomb gets engraved until after it is occupied, and *nothing* else may be built on the tomb level, except for staircases and water/magma pipes. The nobles get their own area of the map, very spacious, and with almost the same design standards as tombs (symmetry, everything fitting together); these will always be seperate from the rest of the base via lockable door, and include, towards the center, a number of lever-controlled cages containing all prisoners of war, to be released in a semi-anual hunt. Who hunts who depends on how good the catch was, that year.