Flying on Virgin America for all flights. There policy online says:

"Our no-show policy is simply that, if you fail to check in, Virgin America will cancel that flight reservation and all subsequent segments for continuing or return flights. On non-refundable fares, the fare or Elevate points spent for all such reservations will be forfeited. So please contact us within the appropriate time and we will gladly reschedule or cancel your flight. If the fare is refundable, then you can contact our call center for credit. Again, change/cancel fees may apply. "

Since it's the return flight and I've booked a separate ticket, I'm thinking it's OK. Of course...they won't share this 'hack' with you.