Granite gorge is located 15 kms outside of Mareeba.
I've been to granite gorge twice. Once on a day trip with my partner and once camping with two kids.
Camping is fantastic with facilities on site. There is powered or non powered sites, showers and toilets.
On entering the park you are provided with a map outlining the various areas you can explore.
You do need a level of fitness, however can take the track as slowly as you like.
In one area you can hand feed the wallabies, another you can see turtles in the wild.
If you keep following the rocks around (some climbing over rocks required) you will come to a place that is advertised as dinosaur footprints.
On the day trip we took a small picnic in a backpack and sat on the rocks to enjoy.
It isn't a highly tourist populated area so majority of the time you will find you are alone.
There is no rush to how long you can spend in the gorge and you could easily spend a whole day there.
If you don't have water with you there is a small cafe to purchase at before you enter. I'd also recommend plenty of sunscreen as there are periods without shade.