Is Pappas Bros. a nice enough restaurant for a new dress?

The company my husband works for has an annual Christmas dinner and in recent years we'e been doing it at the casino and eating at Vic and Anthony's or Ember and staying the night at the casino. It's usually a pretty good time but also kind of tiring. This year they got rooms at the Marquis I think and we're having dinner at Pappas. This is literally the nicest thing that my husband and I do all year and even on vacations we don't do anything upscale. I hate change and unfamiliarity and I'm super anxious and self conscious. At the casino you can blend in wearing just about anything. I feel like that might not be the case here. There's only about 20 of us that even go to the party and the bosses wives always have a costume change before we go to the bar. I always feel ridiculous in the black cotton dress that I wear only for this "dinner party" or funerals but a cursory search shows it just a steakhouse. Is it upscale or anything goes?