The following lounges are available for you to use, if you want to lounge hop:
Lufthansa Senator/Business lounge in T2A, right after exit control.
Then it's a long walk way to T2B where you can visit the following lounges:
Air Canada Maple Leaf Lounge
United Club/Global First Lounge
(Singapore Silver Kris lounge may be open by next week, still under renovation currently)
GFL is the only First class lounge so it should be the quietest. I've read great reviews about United Club so I imagine GFL would be even better.