Thanks, everyone. I'm off tomorrow; we'll see how it goes. I'll probably try the JAL lounge because it's there, but based on belle3388's comments will probably not get in. I'll likely end up at the public facility in the Lufthansa terminal rather than the 100 eur day room. Quicker too.
Not a priority pass member; mostly CO/UA and have lifetime club membership there so don't think it makes enough sense to pay to join that, but thanks for the suggestion, MSPeco.
FTF
P.S.: Delta management: I'm suprised you are flying 3 widebodies a day into a business destination and don't provide a facility for your arriving business flyers. I should have stayed with *A but saw a chance to save a few dollars. That was a mistake I won't soon repeat.