I am on the verge of needing to buy a ticket with short notice from here to Denver, and the best times for flights are on United. (UAL). Checking prices the lowest restricted fare is $849 round trip, but the lowest first class fare is $900!
There are restrictions on the first class fair but it does provide some flexibiity to change without penalty, etc.
And of course, as jerrycoin might note, the FC Cabin is a licensed "pharmacy," dispensing "medications" in great amounts for the 2.5 hour flight