I was just at MCI this past weekend. UA is in terminal A. The gates are all together and have a dedicated security screening point (two x-rays, one WTMD, no premium line). Check-in should go quickly, although the kiosks are messing with infrequent traveler's heads. If no one is using the kiosks, jump the line because nobody will move unless told (that's what the agent told me). If there is a kiosk line, use the premium line regardless of your status to avoid the infrequent flyers.

Checked bags need to go through the TSA scanner between checkin and the gate area.

Security is not TSA (private contractor) and they generally require shoes off. Since the gate area does not have restrooms or food, there is usually a last minute rush when the flight is called, so there may be a line.

Since MCI is relatively close to ORD, any flow control situations at ORD will delay you at MCI. Sunday, they held off on boarding until they were about 45 minutes from projected wheels up -- although those times move around and they want people to stay close.