I took a few pictures on my iPhone of stuff I thought was awesome:
http://imgur.com/U36kq (history of evil)
http://imgur.com/t4AGw (she is dead)
http://imgur.com/xx6Pr (so many choices)
I found a rat den where a radio plays The Nationals Exile Vilify. I missed that in my haste on the first playthough. I really like games where you can explore and find cool stuff. Playing through Portal 2 again is still really fun. The puzzles are still fresh even though the solution isn't too far away in my memory.
At the point where Wheatley pops off his rail and you have to pick him up I just kicked him around the room until he got stuck. I remember an article where the actor that played Wheatley said most of his dialog time was spent recording lines most people wouldn't hear because they dont go the wrong way or take too long to do things. This time I am going the wrong way and taking too long to do things. Haven't heard any looped dialog yet.
When Portal 2 was nearing release they put out the free comic called Lab Rat. You can download the comic and the entire 64 track soundtrack on their site for free: http://www.thinkwithportals.com/media_19.php If you haven't read the comic, you should its really good.
Lab Rat was one of the few comics that I read many times over. It ties neatly Portal -> Portal 2 and asks some questions the game really doesn't answer. The Rat Dens are obviously the product of the guy from Lab Rat but I wonder if this guy will make an appearance in a later Portal?
Looking forward to making my way through the rest of the game for the second time.