DH and I are in a similar situation. You worded your question well, so I'll be looking forward to the replies.
DH FIRE'd from the Rat Race in June 2013. His little micro-business on the side yields $8000-$10000/year after expenses. You're smart to withhold that 15.3%...it made an impact on our 2014 tax return. You definitely don't want to overlook that expense.
Currently, I put (almost) the max $17,400 into my 403b + we both fund our Roth IRA's fully.
I'm wondering, first off, if YOU max your pre-tax retirement contributions? Do you BOTH contribute to either Roth or Traditional IRA's? Are you creating/contributing to your wife's Solo 401 to keep yourself from bumping into a higher tax bracket?
We probably won't get to DH's 401k solo until I've fully maxed my 403b to $18,000 this year, AND find ourselves approaching the next tax bracket. Instead, we fund the taxable brokerage and college accounts.