I brought the whole family to Grace Hopper 2012 in Baltimore when my daughter was ten months old. We made a road trip out of it, visiting some other states along the way. Since my husband was also registered for the conference, we made use of the daycare a lot during the day, and once in the evening for the sponsor night party. We were really happy with the care, and I was easily able to stop in and nurse or provide expressed milk as needed. We noted the fun the older kids seemed to be having when we caught glimpses of them on their scavenger hunts and such.
This year, my daughter will be almost six, and we have a son who will be 7 months old. The whole family is coming again so we can hit Disney afterwards. I figured my daughter would have a blast in the childcare, where her outgoing personality would means she'll easily make some new friends. My husband, who is currently on parental leave, will mostly take care of our son, but I signed our son up for a day of care as well in case daddy wanted to play tourist a bit.
If you want to sign up for childcare, the deadline is September 20. Make sure you have a good idea of when you'll actually use it, because there is a charge for missing sessions you sign up for. Otherwise, it's totally free!
Get all the info on the childcare page of the conference website.