Go over all your ceremony details with your coordinator or whomever is assisting you with your rehearsal and ceremony before the rehearsal.  There is nothing more frustrating and stressful for a bride than everyone at the rehearsal offering their opinions because they can see that there is no orgainzation. 

You should go over family seating at your rehearsal especially if your family has an extended family with Step-Parents or parent's partners.  You want everyone to feel comfortable and not left out so knowing where they should sit and if they are involved in your processional/recessional avoids hurt feelings and ensures that you won't be bothered with seating questions on your wedding day.

Traditional seating for parents is with the bride's parents seated in the first row/pew on the side she is standing and the same with the groom's parents allowing for only a profile view of each of your faces.  If you want your mom or dad to see your beautiful, beaming face during your ceremony consider switching sides.  We would say that 80% of our brides and grooms opt to switch sides.