Flexible working, and a culture where it is actively promoted (as opposed to grudgingly given and sneered at).
As my children have got older, my needs in terms of flexible working have changed. When they were babies, it suited me better to do fewer, longer days, so there were fewer days at nursery / childminders, and clear days that I had off with them. Initially I did 2 x 10 hour days. My boss was a sexist old codger, and told me from the start he didn't agree with part-time working.
Now they are at school age, I do 4 x 7 hours a week. I like being able to collect them from school and do homework, and still have a day at home to do things around the house.
Annualised hours on top of core hours are good - so I can juggle home and work demands as they arise.
I am fortunate that I can take annual leave during the summer holidays, but I am aware this can be a challenge for others.
Dealing with children who are sick is a challenge - I am fortunate that I can bring work home (although only in the short-term), although this isn't appropriate for all types of roles. Something to support parents in those circumstances would be good.
My point is that needs will change over time, and a flexible approach is useful.
My DH has just been granted working from home 1 day per week, which means he is able to collect the DC from school that day, thus allowing me to work later to get my desk cleared. This has helped our family life enormously, so it isn't just about offering it to women. In fact, I think this is probably a massive issue - helping Dads to help out, so the childcare arrangements isn't seen as only the woman's preserve.