ha, thanks! I've slept in the terminal too and know what your pain. I can't actually pay for business class unless they make it cheaper than economy, so I use frequent flyer miles/promotions/credit card bonuses. If you're US Based, I would recommend a credit card that gives you Priority Pass. many have annual fees waived the first year, so that helps. Priority Pass is an international airport lounge program with lounges in almost every airport in the world.

Some lounges you can actually just ask and they have a fee. LoungeBuddy has a pretty good listing of prices: https://www.loungebuddy.com/LAX/oneworld-international-business-lounge-international-terminal-hsBdRwkVbM?booking_date=12-09-2019&source=homepage

I know for Narita airport, if you have a long layover you can do the free transit tour. That gives you access to the ANA lounge which is also really nice: https://www.tripadvisor.com/ShowUserReviews-g298161-d10333820-r534760250-Narita_Airport_Transit_Stay_Program-Narita_Chiba_Prefecture_Kanto.html