Dress, would you say casusl, or would someone need to wear a dress?

Casual is fine.

I work there and people usually dress how they feel, comfortable or classy. Whichever you prefer and are more comfortable with.

My wife manages the tasting room there, and yes casual attire is fine.

I have worn jeans and a t shirt and never felt out of place. I went during the day though with only a few people there