If they're okay with one layover, how about getting both the personal and biz version of the Chase Southwest Rapid Rewards PREMIER Card - that'll give them 100,000 points. Have them charge $10,000 to the card between now and January 1, 2013 (but don't hit $10,000 before Jan 1!). They'll then get the companion certificate for a full two years and they'll only have to pay for 1 adult for all of their trips.

You could think to do the biz and personal premier card in the spouse's name two years from now to get another two years worth of free companion flying, but who knows if that'll still be around then.