Common guys...why does everyone worry about this non-issue...Wear whatever makes you comfortable and what the occassion calls for...
Personally I feel more comfortably, psychologically that is, when I'm well dressed. For my first dinner I wore my brown suit, French cuff shirt and no tie. I looked totally different (akward, perhaps) because the other applicants were in jeans. Second dinner, I was tempted to wear jeans (sort of my night-life outfit) in order to fit in but I didn't feel comfortable in that. I eventually decided on dressing up again but no suit this time around.
Bottom line...dress however you deem right as long as you don't appear too "street" or appear to be peacocking.
Proph..