One thing that really seems to help is to make sure that your villagers have plenty of food, a bunch of farmers, several trained doctors, then leave the game off for several days. More often than not, you'll turn the game on and find that you have had several villagers live beyond the age of 90. Don't do this if you're not willing to have villagers die, though. When I've done this, there have been only deaths from old age, since my village was healthy and well established, and I was just going for the Ancient Elder award.
I'm glad I found this thred as I been trying to get my villagers to live past 90 always die around the age of 84 at the most and even tried to have some just on one skill. I will not turn on one of my games for 5 days. I got lots of farmers and females on parenting on then leave it off and I have several doctors.
PS Linda said she has a few villagers that have lived past 90 and now I know why, She did not play it for several days, as she was staying at her sisters