I agree with what others have said. In certain airports like AUK, LHR, and FRA to name but a few the trans-ocean flights will arrive quite early in the morning, sometimes too early to be able to get into a hotel room. Other times the layover is too long to hang around airside but too short to tour the city..5 hours or so, and the lounge is handy.

I have also used it when arriving at 5 but not getting picked up by a colleague until 830.