Well all this is IMHO, but I think Holden values the "maternal" qualities women generally posess. He's ultimately concerned with protecting the innocents of this world from the "phonies", and mothers do exactly this for their children. In his mind, women are less likely to be competitive and less likely to take advantage of others.
It's a fantastic book... one of my very favorites. Hope you enjoyed it.
l2c
Edit: Impress older women? Hmmmm... I had read your question wrong. Well I think the reason he tries to impress that mother of his schoolmate on the train gets at the same reasons I quoted above. His own mother doesn't seem to really care much about his thoughts and feelings--she's quite detached since the death of Allie. Perhaps he is seeking love from others capable of giving it?