12 days in the BNE area with 2 kids - recommendations?

We're a family of 4 that will be travelling with 2 little ones (will be ages 2 and 4) in May 2020. Flying in and out of BNE. My wife and I backpacked up the East coast (Sydney to Cairns) for 7 weeks about 12 years ago so we're not first timers. Given we have 2 little ones however, we are looking to keep it simple and ideally looking to spend most of our time on or close to a beach that is within about a 3 hour drive of Brisbane. Our initial thoughts were to stay in a couple of different places in the Noosa area and maybe do a day / overnight trip to Fraser Island (renting a 4X4 ourselves), but this is based on our last trip 12 years ago involving stops in Byron Bay, Surfers Paradise, Brisbane, Noosa and Fraser Island.

Any recommendations of places that we should look to visit with kids? Ideally 1 or 2 places for the trip so that we're not constantly moving around.

thanks