Can anyone please advise if they have any experience on what is UA's policy and what they actually do if you decide not to get on the plane on your connecting flight on the return.

I am flying LAS-IAD-LAX-LAS.

If i am not carying any luggage and don't take my connecting flight in LAX, what will UA do, in form of penalties etc. Any idea what options i have?

Thanks
lohiadk