Under-appreciated fact about SF: your kid's schooling choices are either winning the school assignment lottery, having a 50 minute commute, homeschooling, or moving to a city that actually handles things sanely and has lower housing costs to boot.
If instead you choose to send your kids to a public school that provides good educational opportunities, factor in either several thousand in additional local property taxes [1] or similar amounts in donations to the school PTA [2].
[1] http://www.paloaltopulse.com/2014/10/16/palo-alto-pulse-asks...
[2] http://capta.org/pta-leaders/run-your-pta/finance/fundraisin...
quality child care or private school is +$2k/month/child
+2bdrm housing $4k
food/transport/other $2k
for couple with one kid you're at $8k/month post-tax or $150k/year pre-tax to break even.