Alaska miles are some of the best in the business as they have partnerships with lots of airlines around the world including Emirates, Japan Airlines and British Airways. While they can allow you access to some of the best business and first class redemptions, there are also some great economy deals to be had.
Within the US trans continental flights are the best value. It costs the same to travel from NYC to Boston as it does to San Francisco.
More and more airlines are charging high taxes and fees for mileage redemptions. Which in many cases make them absolutely pointless as fares keep dropping. You will see this with most British Airways fares you come across.
This is what is great with Alaska along with the fact that if you actually fly with them you get miles based on distance traveled, not the cost of your ticket. So if you cross the country a couple of times a year they are easy to accrue by flying. Earning miles in economy on a plane???? Get out of town.