My DS was 15 months old when his sister came along..he got to see me in labour for a few hours and the look on his little face was to much he was very worried for his mummy even at that young age, it was time to drop him off well before we did, luckily I had my parents watching over him. I am surre he would'nt remember but i would'nt be able to feel happy about it.
Family day care might be a good option, they do occasional care and have children overnight, I am sure if you worked in with them and dropped your little girl off when they had a quiet spot she would get to know the carer..before the time came..
I also would'nt write your neighbours off, especially the older ones, they possibly have grandchildren off their own and would be quite willing to care for you baby girl when the time came, even prepred to take a day off work if nessecary... if someone asked me I would be only tooo happy to help.. I say introduce yourself and if you feel the right vibe meantion your predicatment, if they are willing they will offer.