We are a two income family, and both DH and I have been in our jobs over 20 years. I work in supervision in county government and DH as an operating engineer for a coal plant. We both have fairly secure jobs, are subject to seniority rules when it comes to lay-offs and we do not need both our incomes to survive. For our situation, having 6 months worth of expenses works for us.
I feel very strongly about having an emergency savings account. Just this week our furnace died

, so we dipped into our account to the tune of $5000+. Having cash available can help you in other ways in situations like ours. The company we used to replace our furnace gave us a 2% discount for cash. We will now work over the next few months to rebuild our account balance to the pre-furnace crash level.