You could do the following PHL to SMF. Friday evening flight return Saturday at 12:20am
PHL leaves around 5pm arrive into SMF around 11:30 pm with a connection in IAH. SMF leaves the next day just after midnight and returns you to PHL in the morning. I have seen it at 273.xx or so.
With a child might be tough.
I did this for 6 months last year. Week in and week out. 1/4 of the time I was booked into FC at the coach fare, and about 1/2 the time I was upgraded.