I'm guessing you are mid-atlantic based on the sates you've done.
Ohio's best race hands down is the
Flying Pig. If you prefer a flatter course then
Columbus is great. Columbus's name sponsor is Nationwide Children's Hospital and a few years back they changed the course so both the half and full run past the hospital. The years I've done it they had some of the kids out there and it was very inspiring.
KY has the
Kentucky Derby festival races which has a half and is a lot of fun. Louisville is a great city and the race runs through Churchill Downs. If you go there make sure to eat at
Hammerheads. It is my favorite restaurant in the country.
For Illinois most people aim for a Chicago race but I really liked the
Illinois Marathon. I did the 5K and Half I-Challenge and the combination of the rural course starting and finishing in a college town was a lot of fun.
I'm on a quest to run at least a half marathon in every state and there are some I really want to do but I don't want to recommend a race I haven't run myself.