Sydney to Brisbane - Costal but still with CBD in reach

My family and I are looking at moving from Sydney to Brisbane during October some time. We would like to live closer to the coast but still be able to travel to the CBD for work within 30mins or so. We will have 2 young children under the age of 5 and need access to the childrens hospital for regular appointments and a great day-care. We want a newish house and are looking to initially rent, budget is $400-$450 for a 3 or 4 bedroom house. I really liked the look of Redland bay/Mount Cotton, but hubby feels that is still an hours drive into the CBD. Any help is appreciated.