Istanbul Turkish Air - World's finest airline lounge?
Crowding can be a problem but I rarely find the downstairs to be over crowded. When it does get very crowded it can be difficult to get a wifi signal.
As for privacy there is this really nice room to the right as you walk in full of lazy boys. Would be a great place to relax if they didn't insist on blasting music from the tv. I spent four hours in the lounge this morning and they were showing a Coldplay concert in there. Very loud. Oh well
One thing I don't think anyone's ever mentioned in the voluminous number of threads on this lounge - it is fantastically easy to meet people here. There are hordes of people about, some killing many hours. If one isn't shy it is an incredibly easy place to strike up a conversation