I had a long run around the lobby and it's not really as complex as I first thought, I guess it really is a case of just learning it. The thing that probably throws most people is:
You've got these stairs here, and then there are stairs to the left which serve the same function (or connect the same areas anyway) and basically sandwich the door at the back. And the wall that I'm pointed at cuts off the little alcove, which gives the lobby (the impression that it has) a lot of small areas. What I was thinking was moving the stairway into this little alcove (so you couldn't see the stairs in the left area in the screenshot at all) or removing the little wall that separates the alcove from the left area (and maybe move the stairs so they come into where the alcove area is). Also the drain overlay on the right is huuuge. Anyway it wouldn't be a big change but it might help it flow a little better, and you wouldn't be left with two staircases that are mirrored (sort of). Hope that made some sense. I can probably draw some better pictures..
edit: here I drew a stupid picture:
Basically leave the area highlighted red as a room that focuses solely on the exit door, and the stairs can swing round in a z shape. Then the room at the back can be used to get to the top floor. This way is gives the lobby (from top to bottom) a room/area structure like "up - exit - up" rather than "up - exit - up - alcove space" god this makes no sense i'll shut up now.
also the pipes here aren't on the wall: