Snorkeling advice for Australia

As an Australian, I'd say Queensland, and the Great Barrier Reef specifically. That means you'd be staying in Cairns, Port Douglas or the Whitsundays, most likely. For snorkeling, you're best off visiting during the dry season (May to October).

Our snorkeling trip was disappointing. Cloudy water, the small chop and wind made the snorkeling hard. There was few fish and uninspiring coral reefs. The trip included 2 stops. I wouldn’t waste my time flying north to see the Great Barrier Reef. It was part of an Australia tour.

To start off, the reefs will be intact well past my children's lifetimes, so I am sure that you have plenty of time. All reefs in the world do have bleaching events from time to time but do recover, as the GBR has done in Australia.
As the Great Barrier Reef is the largest in the world, you have plenty of places to choose to enjoy this natural wonder, depending on budget and time of year. There are also easily accessible coral reefs of the coast of Western Australia, most notably Ningaloo.
The majority of tourists choose to visit our GBR from Port Douglas or Cairns. The best time to visit is during our winter months as PD & Cairns are in the tropics and subject to cyclones and heavy rains in the summer months. If our summer is the only time available to you, then Ningaloo works or below Rockhampton at places like Lady Elliot Island

Look into Lady Elliot Island. We were there in July, and it was amazing.

https://ladyelliot.com.au

If you do a search for best snorkelling in the Great Barrier Reef, many sites will recommend Lady Elliot Island, which is why we chose it.

That said, healthy coral isn't doesn't have the vivid technicolour that you sometimes see in photos. It's more muted, with lots of greens and browns. The reef around Lady Elliot Island is very healthy.

https://simonmustoe.blog/what-does-healthy-coral-reef-look-like/
https://hakaimagazine.com/news/we-have-unrealistic-beauty-standards-for-coral-too/