Best website for finding lowest airfare? Please don't give me the obvious?

We're looking for round-trip tickets and hotel for a trip in about a month. We've searched all of the obvious sites (yahoo, orbitz, cheaptickets, travelocity, priceline, etc, etc, etc. . . . plus many of the major airlines sites directly. Can anyone help? p.s. I won't pay any website to join their "club" in order to view discounted deals. Thank you!