There is no Torah obligation (as far as I am aware) for kibbud for a wife; however, in my experience, husbands tend to show a special honor for their wives. An example where this is frequenetly manifest is on Shabbos when the husband will often give a piece of challah to his wife before giving to any of the guests at the table.
My question is: if the husband's parents are at his Shabbos table, is he required by kibbud av v'eym to give them challah first? I am also asking the more general question: does kibbud av v'eim always trump kibbud for a wife?