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?