I agree with your mother that the arch is way too over the top. If you would like an arch I would look for one that is plain and add your own decorations to it, like ivy or your flowers. Your wedding location is beautiful, I don't think you will need to decorate very much. I really like the pomander balls. Are you going to have them at tables or down the aisle. I personally like down the aisle. Good luck with your wedding, i'm sure it will turn out beautifully, no matter what you decide.