Funnily, I live in PEK and my mom lives near JAX, so I do this drill fairly often. The only way to pull it off with a single connection is via DTW. But, if I'm not mistaken, ATL-SEA-PEK is a single flight number with no a/c change. Also, biz on KE is frequently cheaper than M on DL. The trick is to call a few Korean travel agents. My technique for finding them is to google travel agents in Los Angles using K-town zip codes.