I think that adding Saturday would make it easier for people to know what day of the week it is without checking. That's the day we are talking about having DS' party as well Probably easier than Labor Day weekend.
I think with or without is fine totally up to you. Depending on how many would make my decision if I had a ton to write I would skip it and make people look at their calendars otherwise write it if there weren't too many.
Re: Do I need to put......