Remember, contributing to Roth is post-tax, so whatever tax bracket you are right now, the money gets taxed at that rate. Because your wife's source of income is from your's, it will be same. IMO, it's best to max out your 401k than the wife's Roth to get the full deduction.
I like to have 3-6 months in my emergency fund. Some consider your Roth to be an emergency fund (because you can withdraw your contributions any time penalty/tax free), but I disagree. It's for your future. I opened a online savings account that has a 1% interest rate to put my emergency cash in, not much, but atleast it's better than .05%.