Some aspects of the individual room are the asthetics. if you like 3x3 --great, if you want 2x2 go ahead.
If you want something wacky sure why not?
I tend to work with 11x11 (internal-size, easy cursor definition) blocks within 13xx13 (externally evident) block sizes, separated regularly by corridors, and mould the internal plan according. Fully open for communal areas (with either corner-pillars-only or column/no-column), but internally divided into four (5x5) rooms, six (3x5) rooms or nine (3x3) rooms, with doors(/doorways) accordingly.
'Regular' quarters-block, houses six.
...............
.#############.
.#++++C#c++++#.
.|++++B#B++++|.
.#++++c#C++++#.
.#############.
.#++++C#c++++#.
.|++++B#B++++|.
.#++++c#C++++#.
.#############.
.#++++C#c++++#.
.|++++B#B++++|.
.#++++c#C++++#.
.#############.
...............
This is for normal individuals (and doubly-normal married couples, by extension)
B=Bed, C=Cabinet/chest, c=Chest/cabinet, |=Door, + is area of room.
'Suite' quarters-block, houses *one*.
...............
.#########-###.
.#*+++*#*+++*#.
.#+++++#+++++#.
.#tT+++|+++Tt#.
.#+++++#+++++#.
.#*+++*#*+++*#.
.###-#####-###.
.#*+++*#*+++*#.
.#+++++#+++++#.
.#S++++#++++B#.
.#+++++#+++++#.
.#*+++*#*+++*#.
.#############.
...............
This is for a noble (and any spouse).
B=Bed (defines bedroom) t+T=Throne+Table (defines office or dining room),
S=Sarcophagus of whatever kind, - and |=doors,
*=usual positions for armour stands and weapon racks and cabinets and chests and whatever else is demanded,
but I'll also flank the thrones/bed/sarcophagus with statues, if (after all this) our nobilic friend can
do with a bit more buttering up for whatever reason.
(I've also put 12 1x5 rooms into this space, and you can work out what I do there, without a further diagram.)
Where there's an orientation issue, I often flip, diagonally, between "doors opening E-W" and "doors opening N-S" between adjacent blocks. Nobilic suites generally have their single entry on a facing wall closest towards the main hub (and symmetrically, usually rotationally, where there's ambiguity).
Normally I leave all walls and floors as natural[1], but smoothed, as I dig out the rooms (in material that I
want quarried, and often at least partially to use to make (frexample) marble furniture to put back into one room). While constructing, one of the rooms may be tasked as a material-specific masonic workshop to blockify/furnitureify the local materials, although usually at the opposite end of the 'block of blocks' from where I'm currently putting people's rooms, and so by the time noise could have become a problem he's produced enough items to make it unnecessary for the foreseeable future. I may also task various pre-dug rooms as stockpiles for the furniture items, but this has no noise issues (and, after undefining a 'bed-space' spot from being stockpile, can even continue even after actual residence occurs if I'm lazy).
(Yes, I tend to be a bit OCD about this, beyond most practicalities, but it's all easily doable, and not usually my most intensive bit of any 'semi-mega-project' aspect to my fortress design.)
[1] One noble who
loved a certain mineral got a nobilic 'sub-penthouse' where I'd actually dug into a huge vein of the stuff and then rewalled (and floored) what bits
weren't that material so that they were constructed them in his preferred material, and arranged for every bit of furniture (except for the bed) to be a Masterwork version of that furniture in that given stone. I know some people think I spoil my nobles, however.