'Attentive' means observant, paying close attention, or showing care and consideration. A good hostess being 'attentive to the needs of her guests' means she watches carefully for what they might need and responds thoughtfully - she's considerate and aware. 'Assertive' means confident and bold, 'avid' means enthusiastic, and 'averse' means opposed - none of which capture the quality of caring awareness and consideration that 'attentive' does.