VK is actually about 5 minutes from Churchill Downs and would be an excellent lunch spot prior to hitting the races. Do not under any circumstances go to Asiatique. Some of the places you mention may already be booked for Derby such as Corbetts and 610 Magnolia. I would call them right away.
For dinner I would recommend Corbett's. Also, 610 Magnolia, 211 Clover, Seviche, Asiatique, or Proof on Main.
Lunch, maybe Mayan cafe, Roots/Heart &Soy (vegetarian), Garage Bar (weekends are open for lunch), Doc Crow's, or Blind Pig. Rye is a new place that just opened but I haven't been and it is dinner only I believe.
Jack Fry's is a good rec. I've had several good experiences there. My last visit I was somewhat underwhelmed with scallops which were more rubbery and steamed when they were supposed to be seared but I wouldn't hesitate to go back again.
I've actually never been to Vietnam Kitchen. I've always wanted to go but from a location standpoint it is never really convenient. I've heard more good things about VK than any other Louisville restaurant so I would put that on your list if you have any interest in Vietnamese cooking. If you do go I would avoid Roots as they may be very similar. Also if you might prefer a more modern take on Vietnamese you may want to consider Basa which is very good but overall I suspect you'll get more bang for your buck at VK.
I can't say much about Vincenzo's. It has been several years since I've been. It has been good in the past and may still be. I just never really hear very much about it anymore. If you are interested in Italian food Proof on Main has a lot of Italian influence and their house made charcuterie is very tasty. I've had some hits and misses but lately it has been more hits. A recent tuna sashimi dish was quite good. Certainly not inexpensive and service can be spotty. I believe a server 'John' took very good care of us the last time we were there but can't be completely sure of his name. Another newer Italian influenced restaurant is Mozz. I've been once and it was decent but service was terrible. It was soon after they opened so hopefully that is better. Also we sat in the lounge as opposed to the main dining room.
The last time I went to the Oakroom was right after Todd Richards left so probably not a good time to judge it. Overall I just thought the quality/price ratio was very low. Like many fine dining restaurants with dishes that shoot pretty high, one missed note really ruins the whole experience. Too many ingredients that didn't work together well and small portions plus very high prices. Like I said that was a transitional time for the restaurant and things may have changed. That said, their sunday champagne brunch has always been excellent. Corbett's and 610 tend to run the same QPR risk but I think they are more consistent on the quality side. Also 610 recently started a more value oriented menu/pricing and although I haven't been since that change I suspect it has helped a lot.
Here is a helpful link:
Also keep in mind going out on Derby night is like going out on Valentine's Day. Restaurants inflate prices and try to cater to a large amount of people that aren't particularly used to going out to eat all the time. A lot of places limit their menu to a "special" prix fixe menu. Also, if you want to try a Hot Brown I'd go to The Brown Hotel's lobby bar in the late afternoon.
Hope this helps