As far as my using a nanny, I think it's the best option and my W will for sure ask how I plan to watch my son while I am working, even if I am working from home.
My W is currently working part time away from home and working from home on her off days. Because of that, my MIL is the primary care giver to my kids right now. My MIL is in her late 60's and cannot keep up with my kids, especially my S2. I would think the combination of my working from home everyday and having a nanny assist me would be at least as good as my W being gone three days a week and having her MIL watch the kids.
Me-40,W-37 D7, D5, S3 Separated Oct 3/2013 T 11 YRS M 7 YRS