Originally Posted by Aventine

PUS's smoking rooms are quite small and confined. There are two. One on each side of the sole international terminal. No views of the planes.

ICN's smoking rooms are quite big and spacious. Some have a view of the tarmac and planes. The fresh wall greenery is an interesting novelty but doubt it does very much.

Here's more info for ICN:
ICN smoking area information

Never been to one in GMP so hopefully someone else can chime in for that.