I have a nanny for my 7 month old son. She started when he was 4 months old. I love, love, lover her, as does my son. It is so nice to not have to worry about waking him up and getting him ready in the mornings (especially in the winter) and also to not have to worry about interrupting any late afternoon naps. Personally, I wanted a nanny for at least the first year, because I feel strongly that babies need a lot of one-on-one attention and it is harder to assure that they get that in daycare. But I also understand that most daycares are great places and that babies thrive there as well.
When I was researching daycares, I also found that good daycare for infants under 2 cost almost as much as a nanny (at least here in Manhattan). I am fortunate enough to only need a nanny 3 days a week and that is what we do. It is a small fortune but I think that it is money well spent. If I had not been able to afford a nanny, I think I would have looked for a small home-based daycare setting.
I would not expect a nanny to do light housekeeping especially since you said "kids" and not "kid." When I hired my neighbor to help with my son, it was because I wanted some time to do stuff and he needed attention. If she had split her attention and tried to get housework done, he would be just as ignored with her as he would have been with me trying to get it done.
I had wished many times to have a live-in v daycare for when my kids were sick .. not sick enough for me to have to be with them, but sick enough not to go to daycare . .it would have helped ease that stress. As far as the light housework, etc. it's tough to do both. Maybe a mom's helper would be an idea after school to help out with light chores in addition to a nanny?
I should add that I do not expect my nanny to do light housework. Many families that I know do, but as Anniebrook mentioned, I want her full attention on my son and know that she needs some breaks when he naps. She is very helpful and appreciates that I look out for her so when he takes really long naps, she often offers to do some light cleaning/organizing, which is wonderful.
If you PM me I can tell you what the going rates are for nannies here, but that might not help you, since I am sure the cost is different where you live.