I wish I had read this post a week ago. We had reservations at JIKO at the AKL and when I made the ADR they told me the dress code was 'no flip flops or swimwear, however, T-Shirts ARE now allowed'. Frankly, that means nothing to me, since when I dress up, half of the dress shoes I own are flip flops. *shrug* The day it was scheduled for we decided not to go since we didn't want to waste time going back to our resort, freshening up, and transferring to AKL. THEN we decided that we did want to go, but didn't have time to go to our resort at all and we would have to go in our park clothes. DH was very skeptical about going in our park clothes (even though we did not look grungy at all, I was wearing a plain Pink fitted T-shirt and White capri pants with clean tennis shoes and DH was wearing Jeans, and a White T-shirt with a simple logo on the front). We asked 4 Cast Members if they thought it would be OK, since the 'dress code' wasn't very specific in the first place and they all looked at me like I was crazy and they said we looked just fine.
We went and saw a fair share in khakis and polos, some heels, and dress shirts, but no formal wear to any degree. On the other note, we saw people in jeans and T-shirts AND we even saw some people in sports shorts and dirtier T-shirts. However, I would have felt more comfortable in black pants and heels. Plus, for what you pay for the experience, it is nice to look the part heh.