Where do you take sims for dating or family activities to become closer?

There are several good spots. I usually try to choose the place that fits the character's personality.

But I think one of the best all-around spots that comes with an expansion pack is that park in San Myshuno. It's a large lot with lots of romantic settings. It has things to satisfy any needs that sims might suddenly come up with on their date (toilets, mirrors, kitchen, bathtub, coffee maker, mirrors.) It even has a bar to mix your own drinks, a piano for musical sims to serenade with, and a telescope for horny sims to woohoo.) But the best thing of all is that it is relatively secluded, so you don't have to worry about strangers walking up to you and interrupting your date.