Delts and Traps used to be my least favourite areas to work, due to various breakages and disslocations I've had in the shoulder area, I just have to go lighter to avoid injury & I only use cables, machines and Smith machine - got to think future health and strength so I'd rather play it safe.
Shoulders are quite possibly the area that develops the best(for me) but thats most likely because I work them after legs which is usulay quite a heafty workout!