Just out of curiosity, how does the Boss know that you've got enough miles or have even joined a FFP or that your FFP flies the correct schedule to LAS?
Maybe you're one of those Luddites that have never joined a FFP and just hang out on FT because you've got nothing better to do.
IMO, mile usage for business is strickly off limits unless you'd explicitly agreed to it as a part of your position.