If it is a refundable ticket, why not apply the ticket to a new ticket? This would be an open jaw - MSY/SFO//SFO/ORD - I'm sure you already know this.

If you do find an agent who will book this the way you want it, you can take the non-stop UA 305 which arrives at 10pm. For layovers, only a maximum of 4 hours is allowed. (If I am wrong about that, I am hoping my fellow FTers will correct me.). A two-day layover, I can't imagine you would be allowed to do this, but then again the refundable ticket may allow this. Otherwise, they would only allow you to take the next available flight to ORD and because the next flight to ORD is the following morning you could overnight - maybe that's the max they would allow.

Let us know what happens, it will be interesting to see what you come up with.

UG