Aeroplan allows for very flexible booking when traveling between North America and the US as you can incorporate two stopovers or one stop over and an open
jaw on roundtrips.
United had relatively friendly award routing rules that allowed one stopover and two open
jaws on roundtrip award tickets.Those rules are gone now though and have been replaced by the «Excursionist Perk,» which is essentially a free segment on an international itinerary.
Aeroplan (Air Canada's program) allows two stopovers or one stopover and one open
jaw on a roundtrip award ticket.
Historically Delta SkyMiles has allowed one stopover and one open
jaw on a roundtrip longhaul award ticket.
Not exact matches
On a
roundtrip saver award, you can add one stopover and one open
jaw.
Booking an open -
jaw flight means that you will purchase
roundtrip ticket in which your return flight will be from different airport than you arrived to and / or you will return back to different airport than aiport of departure
on your outbound flight.
United international
roundtrips allow a stopover and two open
jaws which basically allows one to tack
on free or heavily discounted one ways to
roundtrips.
Alaska companion tickets are only valid for
roundtrip tickets, not multi-city itineraries, but there seem to be fairly recent reports of people doing a stopover or open
jaw, or even both, though I wouldn't count
on it.
Flying Blue also allows a stopover and open
jaw routing
on roundtrip awards, so even if you have to pay fuel surcharges, you may be able to get well more than the standard 1 cent per point or less that Citi gives for ThankYou point redemptions.
For partner redemptions, I couldn't find any information
on stopovers or open
jaws, though for partners you can book one way (like American Airlines), you know a
roundtrip can have two open
jaws.