I would certainly recommend a pool with play areas and basketball court etc. I use them alot and they are great teen hangout for when the children age up. A gym is also great for the future. Family restuarant or pub is also a great idea. It can be a bar but with a family feel and equipment. A great way for the kids to be entertained while the adults chat.
If you really arent sure, then place a few houses and families from the gallery with same aged adults and children for your legacy family to be friends with. I love that with my legacy sims.