Aquifer-fed well in the main hall, with a wellroom underneath it accessed by stairs near the well. Wellroom is often where the nobles rooms are adjoined to. This is a short distance from a seperate aquifer-fed waterfall over the only walkways to the drinks and food. I know people keep saying that this means the dorfs will drop their babies, but so far, they've managed fine with carrying things under the waterfall, and everyone is clean. I love aquifers.
All rooms have doors, hatches, or other means of closing them. The whole fort might have more than 250 doors, housing 70 dorfs comfortably. There is always a central staircase, usually 2x2, sometimes 2x3, linking the whole fort together. It has a lot of hatches, lockable in disaster situations.
Bedrooms are in little "halls" with four, six, or eight bedrooms opening through a door into the communal hall. Bedrooms have always been large, even for humble peasant dorfs. Three by three at least, with a cabinet, bed and chest. I've never had issues with dorfs bugging out on their own possession storage, and I like the morale boost. There will be a specific "hall" for dorf children, with the main room having a small binless toy stockpile and often a food stockpile, tables and chairs, and private well. Children can be locked in during disasters, and often are.
Nobles diningrooms and offices are always adjoining, so that you walk through the office to get to the dining room, or vice versa. Often there's a noble bedroom next in the row. If necessary, nobles can be locked in too.
I love huge pillared rooms with polished floors and engraved walls throughout. Furniture is in constrasting coloured stone, and often encrusted with gemstones. I never bother with windows, but doors are usually covered in gemstones as well.