I've got a Green Phantom plec (L200) with 3 Goldfish in a 100 gal. He's wonderful, minds his own business and they all like the same temps and same food.
I used to have my 2 Royal Panaques in that tank with the Goldfish, they were wonderful, too. And unknown to a lot of people-Royal Panaques like temps from 73-86, a huge range. I wouldnt keep a common plec with them though (as the others said). Commons are too big, too active and too pushy with food. Plus they've been known to attach to the Goldfish's slimecoat and the Goldfish can't shake them off.