You are missing nothing at the BA Lounge - it's old, windowless & somewhat depressing. The AF/KLM lounge isn't much better but at least has windows/natural light! Get to the airport as late as reasonably possible & find a decent spot to hang out in the terminal, if indeed are there any at ORD. What a dump!
ORD T5 is indeed a dump! The new global terminal can’t come soon enough. AA flagship lounge in T3 Is excellent if you’re willing to jump through the hoops