Miles vs. cash: When do you use frequent flier miles? Miles vs. cash: When do you use frequent flier miles? - Travel updated 2/29/2012 1:46:00 PM ET Send us your questions and a travel expert may answer them live on TODAY Are you planning a vacation and want to get the most out of your miles? Are you unsure about which frequent flier program is best for you? Send us your questions and a travel expert may answer them live on TODAY. More from Travel