I absolutely agree on the showers. Not very powerful, and hard to find the right temperature.
My best advice on the elevators would be to leave early every day. We left in time for early entry every day and never had a problem. But I'm guessing concierge is on one of the upper floors, which should take care of the problem. I think it's the lower floors that have issues. The only minor delay we had was departure day when we were a little later in the morning (9:30 or so) and we had to wait through several elevators to find one with room for our luggage. We were on the 9th floor.
I had to laugh. Count me in as another one who agrees about the showers!

I've always thought that the showers were a bit kooky but figured I was imagining it. The water pressure is not wonderful -- not horrible, but not what I prefer -- and it is tricky trying to get the right temperature. Often times I am turning the little lever one way or the other and the temperatures seem to go the opposite direction of where I want them to go. It takes some getting used to.
That said, the quirky showers are not enough to keep me from staying at the PPH -- especially with a fantastic DCA view -- but it's one of the things that could be improved.
I may just have good timing, but I don't find that I have to wait for non-crowded elevators too long, too often. It has happened in the past, where an elevator has opened up and it was packed and I had to wait for another one, but usually I can catch an elevator shortly after I press the button. I guess if there has been a delay it has never bothered me too much. I think I am used to slower elevators, though. There are a lot of slow elevators in the buildings around my neighborhood.
I have taken the glass elevator and it was fine, but people know about it so it's not too secret anymore, as
Jenasweetemotion said.
And...the other thing that is often talked about or worried about by future PPH guests is the walk from the PPH to the parks. I don't find it to be all that bothersome or lengthy. Once you get the lay of the land and know where you are going, and are preferably taking the short cut through the GCH, it seems to go pretty quickly.
Janet -- Do you agree, or did you find the walk to be annoying and long?