check out the comparison chart for your kind of flying. If you are flying non-elite qualifying low level miles, and primarily econo, then stick with one program. LH Miles and More will earn you more miles, e.g. 500 instead of 250 for minimum miles on short hops, discount (625 if you are LH Miles and More FTL or SEN level). The problem is LH has somewhat higher mileage requirements for awards. Also you might have possibility of becoming a Star Gold member on AC if your flying should increase in the year. If you split between a couple of progams then you might fail to qualify.

If you are flying an insane amount of miles, then sometimes it is good to split in two or more programs to get benefits with the different airlines. I would stick with AC and Aeroplan or with WS and Air Miles (which some people are looking at very closely now given the changes in Aeroplan).

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