the problem with IAD imo is unless you are leaving from the A Gates or have a few hrs layover its a pain to get to the LH Club and then the shuttle bus to C/D. And UAs A gates are at 1 end while the Lounge is at the other a very long walk And why I said a few hrs layover so that by the time you get there and need to leave to can spend some real time

Now had LH been alot closer to UAS A Gates and Shuttle saving that very long walk that would have been something else