Southwest has fairly inexpensive fares between LAS and DEN that are non-stop. So, I was thinking of doing an open jaw with one of the above airlines and then using southwest to fly between LAS and DEN. Questions: How do I look for open jaw tickets? Do all 3 of the above airlines offer open jaw? Am I correct that open jaw plus a southwest fare would be less than the equivalent miles for "multi-city"? We can also use GSP. Does hidden city ticketing work with FF miles as well? (ie if there is a lower fare GSP_CLT_LAS than CLT-LAS then will there also be more FF availability?) Anything else I should know about open jaw trips? Thanks!