The Morning Calm (F) lounge in ICN is the best I have ever been to. Years back, your SkyTeam Elite Plus was enough to get you in, but now that only gains you access to J. If you are actually flying F, plan to enjoy the ICN lounge (though the J one was pretty good too).

The lounge is huge. It sports great views of the tarmac. It has very large and impressive shower rooms. It has a nice slumber room. Good massage chairs. Large room of computers. Very nice selection of food and beverages.

In my opinion, this lounge compares favorably to any I have been to, including AF Concorde, SQ J lounges, and others. I'll be curious to hear your opinion. My data is almost three years old.