Originally Posted by jetfan
Not much.
C-clss checkin and lounge access at Schiphol and KLM-owned lounges when flying KLM.
After the merger (and before Flying Blue), there was also a time when you could use KLM or AF-owned lounges when flying AF or KLM -- that made the thing much more attractive... For third-party lounges (such as NWA WorldClubs), you could get vouchers for pay.