UPDATE: See a comparison of 4 similar award-travel-selector websites.
If you have frequent-flyer miles from several different airlines, FlyerMiler will tell you which are the most economical to use for a trip you are planning.
For example, a proposed one-way trip from Austin, Texas to Durango, Colorado in Coach would cost 12,000 BA Avios points, 12,500 American/Alaska/United miles, and a jaw-dropping 30,000 Cathay AsiaMiles (using one of Cathay’s applicable award charts).
Delta Airlines, Southwest, JetBlue are not shown.
The website lets you select different classes, like First, Business, Premium Economy and Economy.