Just a quick update:
On that flight I opened up about (out of IAH), I was upgraded somewhere about 24 hours before it and my wife got the airport upgrade (with reseating next to me).

On the way home this week, I was actually upgraded three days out although it looked like first class was almost full. She was upgraded at the gate when one of the booked first class passengers was a no show.

No idea why the return flight, with less FC seats available and less 'blanks' upgraded me three days out while the outbound was 24 hours.