My niece asked me for some advice and I was hoping for some help. (I started to try to research the answer on my own but was soon overwhelmed....)

She is going to be traveling frequently, on her own nickel, between Denmark (Billund or Copenhagen) and Boston. She is based in Denmark. Like all of us, she wants to maximize her ratio of travel travel to dollars. She currently has no miles to speak of.

Obviously, I told her to pick one carrier and a) remain loyal to them and b)maximize accrual of miles from alternative sources (eg credit cards). But since she is starting from scratch, the first question is "which carrier?" I looked at who flies BOS/CPH and the number of carriers was large; often the itineraries feature two carriers/code shares; and furthermore, there is the issue of the airline alliance programs to consider.

Does anyone have any advice on which programs she should consider? Is there some easy way to compare the programs? What features should we look for/avoid?

Thanks to all ! Happy Thanksgiving!

PS, the list of carriers that fly BOS/CPH (including codeshare) include BA, SAS, UA, AA, Lufthansa, Delta, Air France, Alitalia, Swissair, KLM, Northwest, and Icelandair.)