Disney business casual.. Clean jeans, dockers, dress pants. Polo shirt, button down and actually, a clean t shirt with no slogan or logo is allowed now. No dirty ripped sneakers, but nice leather dress sandals are allowed. Most men I see wear boat shoes or something similar.
For women its nice jeans, dress pants, skirt or dress. No spaghetti strap shirts, no flip flops, dirty jean or tees or swim wear allowed for either.
I have worn "tank tops" also called a shell (the strap is at least 1 inch wide and covers bra straps) to Signature restaurants with no problems. I have not seen any men with tank tops on though.
I am lifting this from another thread (It is also my post from there)...
As posted on this site (and many others)...
Business casual :
• Dress shorts
• Dress pants
• Jean pants
• Collared shirts
• Blouses
• Sweaters
• T-shirts
Not permitted by this dress code is:
• Hats
• Swimsuits
• Swimsuit cover-up's
• Tank tops
• Torn clothing
• Flip-flops
Basically, the signature restaurants (the more expensive, 2 credit places) are more upscale and do not wish to see people wandering in from a long day at the park without taking the time to "tidy up" a bit. I have seen people turned away who just came from the parks (still had their shopping bags, overheated and tired) turned away, but I have also seen them seated (after the dress code was explained) waaay in the back away from everyone else. Then again I have seen women in cocktail dresses, expensive jewelry and the like and men in suits at the Concourse Steakhouse.
It says "flip flops", but leather thong type sandals are ok for women, just not the rubber go to the pool kind.