this is a topic of frequent discussion and everyone has a different opinion.

for me i value them at 2.5cpm minimum. my goal is to redeem at 4cpm of value or higher, that is, if i am redeeming for a 25k mile ticket, that ticket better cost at least $1000 for me to feel like i am getting all that my miles are worth. sometimes though, situations necessitate redeeming for less than that value, i refuse to redeem at less than 2.5cpm generally. like everything else i am sure that value will be forced to change with UA's overhauls of the program to make redeeming more difficult...bound to be coming in the future.