I am checking BWI-SEA on co.com. If I select coach for both outbound and return - Co.com incorrectly fares out First Class on outbound and coach for return.

If I change the selection to First Class outbound and keep coach for the return then I get the proper fare for coach for outbound.

This is a better bad error. I now coach is available - as travelocity fares it out correctly and I get co.com to fare out coach - just that I have to check the box for First Class for outbound.