One thing to think about - even if you have a big darkroom, it is really handy to have a nice, largish work area for work that you do in the light. It is also easy to make a work area like that multi-purpose, so other, non-photographer people in the household can use it.

A decent size work table, a good sink or two and counters and cabinets out in good light can be used and enjoyed by the whole family!

Think chemistry mixing, toning, trimming prints, matting, framing, negative sorting etc., while the rest of the family can think of things that they might like to do in a good, well lighted work area.