DD5 loves her playroom, probably because until last year we lived in a much smaller flat with no space. She has a low table for crafts, a normal-sized desk, a sofa, and a ton of those IKEA storage units with the plastic drawers. All storage is labelled, so technically everything has a place (although we only do a big tidy when guests are coming; I don't mind if it's a mess, as long as nothing's getting damaged).
Most successful toys so far are:
IKEA whiteboard/easel, with a rug in front = hours of imaginary school with soft toys doing carpet time.
junk corner: every bit of cardboard crap in the house goes here, and there's also a ton of masking tape (which she can tear herself) plus safety scissors. This has been used every day for weeks now.
Lego
Sylvanian families
Easily-accessible tubs of plain paper, coloured paper, card, pens, glue sticks, crafty bits, stickers, magazines and yet more masking tape. DD really enjoys making 'books', CBeebies-type birthday cards and (I don't know where this came from) invitations to imaginary parties.
Dressing up box
She still does Play-Doh, painting and homework at the kitchen table, and has mostly soft toys and books in her bedroom. But the playroom is definitely her space and I'm so glad we have it, especially as it's our only room without party walls so I don't have to get too stressed about noise.