Of the list of options at the link in your post, I would choose the Institutional Total Stock Market Index fund *if* you're willing to rebalance as your kids get older. It should have rock-bottom expenses, exposure to the entire US market, and is 100% stocks.
If you don't want to rebalance as your kids get older, then I'd do the aggressive age based option.
But those are just the choices I would make and shouldn't be construed as advice to you.