The Romulans were not interested in peace with the Federation. They wanted a foothold in the Klingon Empire to put more pressure against the Federation. Using the Duras was a means to an end for them, and was mutually beneficial. Romulans are only interested in "peace" if it suits their needs. They would have no reason to ally with the Federation until the Dominion threat.
Gowron didn't really do anything to suggest he was as bad as Duras. I'm not sure what you got that impression. We just heard a brief description from Worf in Reunion. By Redemption, all he had done was become Chancellor, see through the Duras sisters' ploy, and leverage Worf. His arrogance and incompetence came later in DS9.