Virgin America Elevate - Booking multi-city Vs 2 separate bookings

Need to book LAX-SFO then 1 week later I need to fly SFO-LAS.

Is there any advantages or disadvantages of doing this as a multi-city booking Vs doing it as 2 totally separate bookings.

Thanks.

This time of year, with weather an issue, it's a good idea to book them separately. If one way gets canceled or delayed, or you don't make it, you don't risk having your return flight canceled on you.