I have been trying to book flights using my 90,000 Frontier miles for 3 years now. They force you to wait for 6 up to 16 hours in Denver before connecting to a second flight from PDX. Their miles expire in 6 months, which is ridiculous. Even if you spend miles, it doesn't count against the 6 months; you have to EARN miles. This is the dumbest FF program I have ever seen. In addition, they mostly charge 20,000 miles each way, so it's a lousy bargain as well. These idiots have managed to be worse than Spirit Air, which is competing for the worst of the worst, they just can't match Frontier for STUPID.