One issue with Delta is that they do not have one-way awards (or to be precise, one-way awards cost the same as roundtrip awards). If you get enough points for a Southwest one-way ticket, you can pay cash for the other leg. The awards are also refundable without fees in case your travel plans change. As other posters have written, Southwest is not the program for international business class, but it is a decent program for domestic coach (although the points will lose about 15% of their value on March 31).