MCI-MDW has gotten crazy expensive on all three airlines. But because so many of them are DAL-MCI-MDW it seems to be worse on WN. I've been on afternoon flights where there are more DAL-MDW through passengers than local boardings at MCI, so WN has no real incentive to price the MCI-MDW fare lower than the DAL-MDW fare.

AA is going to be a mix of MD80s and 50 seat ERJs. UA is going to be a mix of 319s, E-170s, and ERJs, with the last two ORD-MCIs being on ERJs.