what to wear?

Hi there!  My husband has been doing wedding photography for almost 2 years now, and starting this season, I am now going to be assisting him at weddings and I am wondering what would be appropriate to wear.  He always dresses in nice dress pants and a button shirt w/ or w/o a tie, so should I wear a dress?  Just not sure how dressed up I should be since I know I need to be comfortable and able to work in what I am wearing.  Any suggestions?

Thanks! 

Kristin