We live in the SF Bay Area. There are far more working moms than stay-at-home moms, both in an out of the church. My wife often complains to me that stay-at-home moms are looked down upon both at church and among our non-member friends. She's especially self-conscious when it comes to my work parties/socials. Folks will ask her what she 'does'... she'll explain that she's a stay-at-home mom and the conversation usually stops with a long awkward silence.
I also can't think of a single relief society sponsored event in our stake, which occurred during normal working hours. Both our stake relief society president and our ward's relief society president work.