Disney's Signature Restaurants have a "Business Casual" dress code. These would be the 2 TS restaurants.
They include: Jiko, Yachtsman Steakhouse, Narcoossee's, Flying Fish, Artist Pointe, California Grill and maybe others that I am forgetting.
Citricos too.
There is a 2 TS restaurant that doesn't have the dress code: The Hollywood Brown Derby. That's because it's located in a theme park, where people are expected to be dressed in very casual attire.
However, other than at Victoria and Albert's, all of the other restaurants that have a dress code are still pretty casual. Dress shorts are acceptable, for example. Here's the actual wording from the Disney website:
Dress Attire is Business Casual
Men: Dress slacks, jeans, trousers, or dress shorts, short or long-sleeved shirt with a collar required. Jackets are optional.
Ladies: Jeans, skirts, or dress shorts with blouse or sweater, or a dress required.
Not permitted in dining room: tank tops, swimming suits or swim suit cover ups, t-shirts, hats for gentleman, cut offs, or torn clothing of any kind.
Again, this only applies to the restaurants mentioned above.
David