Okay, I'm relatively new to flying Delta (matched over to PM middle of last year) and am facing a situation that runs me into several unknown bits of airline rules, so thought I'd ask for FlyerTalk wisdom:

The Situation: My wife and I are booked together JFK->SLC->JFK. I've had a change in plans, so now need to fly from SLC to the West Coast rather than back to JFK. My wife will continue back to JFK. We're booked in coach (upgraded to C+) on the way out, and in first on the way back. Ideally speaking, I'd like to use RUCs to upgrade the outbound to first, but I think that's looking very unlikely so it's not a strong factor.

Options:

1. Split the reservation now and change my ticket to continue on to the West Coast. This results in a fare difference in my favor, even after the change fee.
2. Book a separate ticket from SLC to the West Coast now, wait until we're in SLC to split the original reservation and cancel my return flight
3. Wait until we're in SLC, split the reservation and change my ticket at that point. I anticipate that this would be much more expensive than #1.

Considerations that I don't know the answer to:

1. If I split the reservation now, will my wife lose her seat in C+?
2. If I split the reservation now, does it affect our ability to upgrade to first using the RUC?
3. If I book a new ticket before cancelling my SLC->JFK return (both flights would leave SLC at roughly the same time), will Delta notice this and cancel one or the other?
4. If I wait until I get to SLC to cancel my return flight, will I retain the value of the return flight less the change fee? (Since the return flight is in F, it is most of the value of the ticket so I don't want to lose it.)

Any opinions on the best route to take here?

#2 runs the risk of having Delta cancel something for you. I don't see the reason to even consider #3.

You can use a RUC for a companion on a separate PNR but same itinerary.

Your wife is unlikely to lose her C+ seat, but could in the case of equipment changes, IRROPS, etc. There is no guarantee she will stay in it.

Does Delta actively monitor for this? I know AA does, whereas BA does not.

Well, if it made a significant difference to the outbound flight to keep the itineraries and #2 was likely to get a reservation cancelled, then #3 is worth considering. But it would probably be cheaper just to pay for an upgrade to C+ for my wife versus going with #3.

I think the OP's best option is to either:

1. Change your reservation now since it's a net cost savings even with the change fee.

2. Do not touch your existing reservation and book a separate one-way to the west coast. I've had similar overlapping bookings on two occasions, booked months in advance, with no problems. Officially, you are supposed to fly what you book. Still, what businessman has not changed flight plans mid-trip? Happens all the time.

Either way, spouse will probably keep E+ unless something like a schedule or aircraft change makes Delta's computer auto-reassign seats.

On a side notes, I've been sorely disappointed by the uselessness of RUC's. Either the upgrade clears withhout them on "easy" routes, or there are hardly any seats available hub-to-hub after Delta monetizes the first class cabin. RUC's are great for LAX/SFO-JFK flyers, though.

I'm inclined to go with the "book a new ticket" option since it also lets me take advantage of (slightly better) corporate rates and will make expense reporting cleaner.

If I go that route and split the tickets and cancel my return flight after I'm already in SLC, will I retain the value of the return flight less the change fee? I just want to make sure I don't waste the value of that segment since it's about 80% of the original ticket cost.

EDITED to add: Oh, I think I found the answer to my question in a different thread (required slightly better searching), so it seems like the answer is I'll get back a voucher less the change fee which is definitely the preferred outcome.

People will dispute this, but I had a friend who was recently booked on two separate tickets that were supposed to be in the air at the same time. One reservation had his SkyMiles number in and one did not (on purpose, so that they would not be able to track the duplicates). Delta DID catch it and called him to make a decision on which he would be using. They have made some major strides in tracking these things.

What was the duplicate info, his name (John Smith)??? More likely, same credit card?

Hmm. I'd actually be okay if they caught it and called me in advance. I just don't want my new ex-SLC ticket to be cancelled silently, which is what AA seems to do when they notice duplicates. (Or, worse, have the whole original JFK->SLC->JFK for two of us cancelled.)

In any case, went ahead and booked a new itinerary; will hope there are no problems waiting til I arrive in SLC to change the original ticket.