I give all my families really nice, colorful houses. I grew up as a military dependent (my father was a soldier) so we had a lot of small, plain houses/apartments with really strict decoration rules (nothing hanging on walls that will make holes, plain white walls that weren't allowed to be painted any other color, no lawn decor, etc) They were always structurally sound and well built, but very plain and boring. So I nearly always give my sims bright, colorful homes with lots of cozy decorations they can enjoy. I wish we had tree houses in the Sims 4! My sim kids would get them all the time.