I miss how in the Sims 2 you could have your household age and then go age the other households when you're ready to age them. I hate that I have to turn the aging off for the entire neighborhood. It sucks. I wish it was different. I have lots of families that I don't want to miss promotions or new births. I feel that having the sims 3 like this is making me miss out. I liked the option in the sims 2 on how we could choose which sims would age with us. Anyone feeling the same way?

I think in the options you can turn off story mode so that the sims in the town will not age but the sims your playing will.

From the manual:

The Sims 3 also features an option called Story Progression. This feature helps keep your town alive and thriving. With Story Progression, your Sims’ neighbors lives progress normally. Neighbors may move away, new ones will move in, friends get promotions, neighbors have children, and eventually even die. Basically, life goes on! This feature helps to keep the neighborhood balanced.

It would simply be too difficult for the game let some people in the town age and some not while it's trying to calculate EVERYTHING all at once.

I actually disagree. I love being able to play one family and marry townies without fearing that they're older than your grandparents. I never switched families in Sims 2 anyways.