If only there was somewhere to sit...
I was in IAD yesterday. One club entrance had a line about 20 people long (I didn't even slow down) and the other was "full" according do the people at the desk.
I went and bought a soda and was tempted to take the receipt back to the club and ask them to reimburse me.
Having actually paid for the membership, that really irks me.
IAD gets crazy busy in the late afternoon and early evening. It's all the credit-card holders I think. Try instead if flying UA to access the Lufthansa Business lounge with a UC membership.