We are having an outdoor ceremony (weather permitting!) and have a ton of picnic table at our disposal which put us as our final decision to NOT rent chairs (took forever to make that choice...) I think having a few rows of chairs at the front reserved for the immediate family will be nice and we'll be able to do but the remaining seating wil be picnic tables lining the aisle. We plan on covering the seats to hopefully avoid any snags on clothing. My question is -- how to let guests know that they can dress 'down' but not like daisy duke down, to make it easier for them to get in and out of the picnic table seating and to avoid any mishaps with nice nice clothes? Thoughts?