Is Telling Christians that Their Obedience Will Bring God's Blessing Harmful Legalism?

Protestants agree that we are "justified by faith alone," and that our good works do not contribute to our justification. And we are often told that "grace" means "God's unmerited favor." But then how can we teach Christians about the hundreds of moral commands in the New Testament? Does obedience to the moral commands of the New Testament make any difference in how God relates to us? Does obedience bring blessing, as many passages seem to indicate? And if so, how do we teach this while avoiding legalism?