I'm a fan of ITA Matrix for flight searches, and The Man in Seat Sixty - One for train (and other forms of overland travel) searches. (theprofessionalhobo.com)
With that, you now know how to use all the basic features of ITA Matrix! (upgradedpoints.com)
You can estimate the surcharge before looking for award space by using ITA Matrix to find the same itinerary as a paid (or revenue) ticket. (travelcodex.com)