No. The plat lounge is very nice and has a great breakfast + nightly snacks + cocktails. They do I think have another lounge for non-plats staying in a top floor but I think the platinum one is better.
Also at the SGW, you can choose to have the full buffet in the lobby restaurant which has a HUGE selection!
Cash+Points is a great value here and it's also very close to Lufthansa centre for shopping/meetings.