We really like the NW area, up along Parmer Lane (734) and 183, all west of I-35. It's a quick dash into town outside of the rush hours and the areas are great for schools and families, plus easy reach of the hills and lakes. Excellent shopping!
Cedar Park is popular with families, so is Avery Ranch and Brushy Creek, or going back towards town the Anderson Mill, Jollyville and Spicewood areas all attract families who want to be within easy reach of Austin proper.
If you Google map the 78729 zip code, they are all within a 5-mile radius (ish).
Google Maps