The ikea expedit cube units are great. As you can get storage boxes for smaller toys, blank for larger toys/books and the higher ones for trinkets/treasured art craft items (these gather rapidly from preschool age!). We have ours attached to the wall so they can't topple over.
The dolls book case is cute but it is expensive for a smaller bookcase, they will grow out of the dolls house cuteness and so long as they have books mine wouldn't care what they are kept in : )
We have normal wardrobes but a shoe hanging thing for swim cozzies, folded trousers and leggings, as they don't have enough to justify a whole wardrobe of dresses : ) at the bottom of the wardrobe is a plastic box for to grow into stuff either bought in sale or hand me down or kept for next year items that are out of season. Shoes sit on top of the plastic box.
Buy bigger storage items than you currently need as toys like playmobil, Sylvanian, Lego etc all take up lots of space.....
We also have the ikea soft storage baskets (2 small, one larger in a set in kids section) to make it easier for them to find things within drawers eg. Basket for socks and tights loose in one small drawer, basket for pants, vests loose in another. Drawers can be big and toddler clothes small so I have found it helps from becoming a jumbled heap.
Happy planning