how about have them fly on UA, and buy Economy Plus tickets? They would get a good deal of additional legroom, though same seat width and economy service.

Another option is to fly "business class" LAX - DAY on FL (Airtran; http://www.airtran.com/Home.aspx). Airtran offers day-of-departure paid upgrades from Coach class to Business Class (subject to availability). The price would be $80 each for the LAX - ATL segment and then $40 each for the ATL - DAY segment. (same prices on the return). Total of $120 per person each way, or about $480 for the whole trip. OR they could just purchase business class tix on FL in advance for ~$900 each r/t, all-in.