I had booked a somewhat pricey ticket to Houston, but was in need of changing dates, and United charges a fee + difference in fare for flight changes outside of the 24 - hr cancellation policy. (pointsfitness.com)
However, bear in mind that there may be differences in fare prices, so if it's a last - minute cancellation, your new ticket may cost more than your rewards points can afford. (mybanktracker.com)
Lufthansa actually has a pretty standard baggage fee policy, you just have to tediously sift through all the various differences in fares and routes. (upgradedpoints.com)