What should I wear to my Boyfriend's holiday work party?

It's a restaurant crowd, being held at a cool restaurant/venue with a live band. Colorful crowd up people, ranging from jeans and t's to tail dresses. I don't believe my boyfriend is planning to get very dressed up, but I want to look nice for him, and honestly hate it when people are more dressed up than I am. I have an emerald green dress which is form-fitting, has some , but I'd probably pair it with a black cardigan or shrug. Then I have a black turtleneck with a white mini skirt, black tights and black heels, or should I just go for a dressed up jeans look? Help!