I'm looking at tossing the return half of a ticket to save about $2,300 pp. We're thinking of taking a transatlantic cruise, which would mean we fly SFO-FLL, cruise and then fly home from Europe. An open jaw on this route prices at $2,960. But a one-way ticket to FLL is $120 pp, and I can get a discount rt ticket from Europe to SFO for about $500 pp. So we'd be far ahead to use 2 different carriers and toss the return tickets.

This is a case where the airline's prices are somewhere between "idiotic" and "obscene" because the open jaw costs significantly more than 2 one ways on the same carrier. Prices like that almost invite pax to "flex" the rules.