You might be better off just changing the return to LAS/ATL/RIC and getting a super cheap ticket LAX/LAS as they can be had for next to nothing. That might be far more cost effective than adding a stop over on a domestic ticket.
Even looking at a flight leaving today on Expedia, tickets can be had for as little as $35 dollars (not on DL but still) So I'd definietly price out both ways