My advice is to purchase a house if you want to live in a house that you own, and want to personalize, and can easily afford. I say this as a 5 year homeowner and I mostly hate the maintenance part of owning a house.
If you do decide to buy a house, I'd honestly do this to keep your budget in check:
Household income before tax
minus $40,500 401k max for both of you
minus $taxes/benefits
minus $12,000 iras
minus (market value reliable childcare*)
equals remaining take home pay, aka $XYZ
Make sure your payment plus utilities plus 1% of the value of the home for maintenance totals less than 25% of $XYZ.
*I say to account for market value reliable childcare because while I personally benefit from my mother's help, and a family friend's cheap services, I know that things can change and I need to be able to afford "normal" childcare at the drop of a hat. My mother-in-law is now out of the picture to help us due to her own health issues as she ages. We had planned on using her for help in some cases, but that's not possible now.
Also, be prepared for the possibility that your wife may not want to go back to work. With our first kid, it was up in the air, but with our second, my wife is firmly in the "would rather work than be a stay at home parent" camp.