In addition to the standard beds, end tables and dressers, I add entertainment items to fill a room. I tend to include bookshelves most often, and sometimes TVs, desks, fireplaces, etc., depending on the available space. Plants, rugs, sculptures and paintings are nice additions, and sometimes I use miscellaneous clutter décor. If I’m designing a room for a particular Sim, I keep in mind their favorite colors or preferred hobbies, like an easel for artists or a display area for collectors.
I will sometimes plan a bedroom using colors from a painting, or take inspiration from the colors from the world they live in. I may choose a shape or pattern and design around that. Themed bedrooms can be fun to create, especially for kids.
Samples of various styles behind the spoiler.