Sounds like you are describing clothing that both drapes and fits well. But all I come up with is boring things like "well-tailored", " coutoured" (which could be spelled better), "custom-designed"...
what if you start from the perspective of the furniture and how a slipcover enhances its beauty while hiding its faults. (like good clothing does--???---)
I don't think this is what you are looking for for an answer, but maybe it will generate a few more creative synapes.