Hotels and even hostels are very expensive in Iceland. If you’re staying in Reykjavik, that’s a 40-minute drive to the airport. If you have an early flight, it’s even more challenging. Many people chose to sleep at KEF airport and it’s not a problem
When I’m not flying in the premium seats, lounge access can still be available to anyone with Priority Pass. My home base is LAX so whenever I’m traveling internationally through LAX’s TBIT, I get to use the Korean Airlines (KAL) lounge.