I have had 3 nannies.
The first one - an MDC mom *waves to chelsea* We loved her. My little girl at the time was around 18 months old and she had just had a baby and it worked out well -she was with us for about 4 months and moved on to bigger and better things. She did well with bringing her little one -I think sometimes it was hard for her to pack her baby up for 6:30 am but she did amazing. I never really felt her having a nursling with her took away from any of Violets care. I think if Violet was more active and they went out it may have been an issue but no problems.
Our second Nanny we found during the process of Chels leaving, I posted on motorcitymoms dot com and got flamed off the board because I didnt pay enough money but somehow W saw our ad and contacted us - she was awesome. She was an young grandma type and she was with us for abit and with me during the birth of our second child.
Our current and third Nanny we found on craigslist. She is great with my girls.
Craigslist is great but oh my god some of the people that show up at your house or the place you agree to meet are SCARY.
We paid for sittercity and often found that people sounded great but never followed through with meeting.
I never paid for care.com but folks looked ok on there.
We personally could never afford a nanny agency.
I think craigslist and watching it DAILY is the best chance for this area. Also word of mouth - call daycares -ask if they have anyone they had to let go, ask your local play and music gymboree, call the universities and ask for education students.
We are very very limited based on what we can pay so it is really tedious to find someone, that and I am a demanding, pain in the butt
Oh - the other thing - I would ALWAYS be open for a mom to bring a child with her but my biggest concern is car issues. We have 2 kids and 2 huge car seats and most cars, you can not safely install 3 car seats in across. Especially if the person is a Nanny - they do not want to dedicate their car 24/7 to their job and lose their backseat. I expect our Nannys to be able to go to a park, library, play center, etc and unless they have a van or a third row - getting out is impossible.