I have stayed on the GC many times and there are plenty of options….
Sea world resort is convenient and often has some great special deals…. seaworld is however rather run down and in need of a bit of a facelift. Thus may have occurred during the covid19 shutdown but it’s worth checking!
A great alternative us to book an air B&B close to surfers paradise. There are loads of them and you could book a 3 bedroom apartment with all amenities for a fraction of the price of a hotel and still be close to the action.

sunshine coast and the gold coast are great. a little more relaxed than the city and much more family friendly things to do.

I’m lucky enough to have family there. They are in Caboolture and Maroochydore. Their pretty good areas to visits

We went to BreakFree Alexandra Beach in the Sunshine Coast. http://www.breakfree.com.au/alexandra-beach/ We had our own kitchenette and laundry. The place was very nice. The bus stopped in front of the resort when we went to the Australia Zoo, so no need to hire a car. I’d go back.

Ashmore is also well situated for getting to the theme parks and they have pools too.

Ashmore Palms is good for families – good range of accommodation and good too. Check it out!

Maybe look at the BIG 4?

I adore the Gold Coast, I have family there and try to get up there as often as possible. Hope you enjoy your family holiday, I know I do