I have some experience with both programs, being gold or higher on one or the other since 1992 and switching twice. My main use is for free travel in coach, and I do like to try to hit different destinations.

While I lean ever-stronger toward CO for my own set of circumstances, in yours I'd actually have to give DL the edge. They seem better on redemptions and seat availability and a can-do attitude there, in my experience. They're very strong to Europe, and SkyTeam is, for the moment, more formidable than Continental alliances. That may change with KLM's integration, though.

Continental, OTOH, has lower award levels (if you can find seats) and some pretty out-of-the-way routes (try the Island Hopper through Micronesia, for example). They also are strong in Latin America and do quite a few award sales there. I'd give CO an edge in that area in general: I went to Hong Kong for 25K miles and Germany for 20K earlier in the year. DL also did a few sales, though. If you can pounce on award sales they're great. It might be worth it to split 50/50 just to play those on both airlines.