I had a discussion recently about the topic of “dressing in your sunday best” at mass on Sundays, and the discussion led into a disagreement of appropriate dress attire at all mass’s, whether is Wednesday or Sunday.
The discussion went something like this. My position was, that although Sunday is the day of obligation, the reason we dress up to mass is because we are in the house of God, and the celebration of the mass is just as important on Sunday as it is on Wednesday. If you wear your Sunday best only on Sunday’s, then its kind of hypocritcal to go in jeans on Wednesdays. (All that said, I’m only proving a point, since I go in “comfortable” clothing to church regardless of what day of the week it is, I just make sure I’m presentable).
The other persons position was, that although true, that every mass is important, Sunday being the day of obligation is the only day one is required to wear their Sunday best clothing. That the weekday masses, although no less important, are more casual (not usually having a band or choir, and lasting half the duration of a Sunday Mass) thus making it ok to dress Casually.
So, to summarize, I think that if you believe you must dress up on Sunday in your best clothing for Mass, then you should dress up in no less than your best whatever mass you go to.