Don't knock yourself out trying to make everything perfect, hoping that this will be the one time that your critical mother or sister or in-law will have nothing negative to say. It's not going to happen. If someone in your circle is an Unpleasable, they're going to have a biting comment about something so out of left field, it can astound you. They can be pretty creative, too. If you clean your house to a shine for the rehearsal dinner, exhausting yourself, there she'll be running her finger over the top of a picture frame just looking for dust. If your award-winning chocolate cake is on the table, there's your sister with a comment that the frosting is a little thin on that side.
I just read in a terrific magazine article that 'complaining is a way of bragging,' and that really made an impact on me. Someone who complains about your cooking or your wedding choices is really saying, "I could do this better." But you know what? They can't, and that's why they feel compelled to point out what your flaws are.
Once you realize that the Unpleasables are really just insecure, you can let go of the maddening tap dance to make them happy, drop the wish that this time they'll have nothing bad to say and that maybe they'll have (gasp!) a compliment for you, you'll be so much happier because you won't feel the need to try so hard. You can lose the pressure and tension, and just go about setting up your wedding plans or cooking your marble pound cake, enjoying it more because you have no fear of insults.
It's a tough habit to break, wanting to please people. But once you get a little bit of practice, you'll get to the point where that zinger, that out of left field insult or critique, will make you smile. It is, after all, a compliment. You're doing everything wonderfully.