What would it take to hire someone to do what your wife does for the household? Or what would it cost you to cut back on work to take care of all of that yourself?
The monetary value someone provides isn't just limited to salary and daycare, so don't limit your analysis to those two obvious things. Try to figure out what daily life would actually be like if your wife wasn't there and you were doing all of it -- transporting kids, handling groceries/meals, cleaning/managing the house, whatever all the other little things are that mostly go unseen. Then figure out what would have to give if you had to do all that yourself -- which would you outsource, which would you cut, which would you need to take on yourself, and how would that affect your own ability to work at the same level you are now? Make a decision with all of that in mind.