Delta isn't going to work to HEL. Alaska's one-partner rule would prohibit the AF or KL connection onward from CDG or AMS. (No, DL doesn't serve HEL with its own aircraft.)

If looking for a Business class redemption originating in SEA, I would try:

SEA-YVR on Alaska
YVR-AMS-HEL on KL

SEA-SFO on Alaska
SFO-AMS-HEL on KL or SFO-CDG-HEL on AF

SEA-YYC on Alaska
YYC-AMS-HEL on KL

LAX can work, too, but that adds a lot of flight miles.